diff --git a/README.md b/README.md
index cd3dd00..197f90c 100644
--- a/README.md
+++ b/README.md
@@ -121,10 +121,10 @@ View the analysis results in a browser.
 This gem is specifically designed to analyze large applications with a modular monolithic architecture. It allows users to categorize each analyzed file into specified modules directly through the web interface.
 
 - `--definition-dir` Specifies the directory where the analysis results are stored.
-- `--module-store-path` Designates a path to save the results that include details on which module each file belongs to. If this option is not specified, the results will be temporarily stored in a default temporary file.
+- `--metadata` Designates a path to save the results that include details on which module each file belongs to. If this option is not specified, the results will be temporarily stored in a default temporary file.
 
 ```sh
-bundle exec diver_down_web --definition-dir tmp/diver_down --module-store-path tmp/module_store.yml
+bundle exec diver_down_web --definition-dir tmp/diver_down --metadata tmp/metadata.yml
 open http://localhost:8080
 ```
 
@@ -151,7 +151,7 @@ $ pnpm run dev
 
 # Start server for backend
 $ bundle install
-$ DIVER_DOWN_DIR=/path/to/definitions_dir DIVER_DOWN_MODULE_STORE=/path/to/module_store.yml bundle exec puma
+$ DIVER_DOWN_DIR=/path/to/definitions_dir DIVER_DOWN_METADATA=/path/to/metadata.yml bundle exec puma
 ```
 
 ## Contributing
diff --git a/config.ru b/config.ru
index 4e9a0d3..7a4ec58 100644
--- a/config.ru
+++ b/config.ru
@@ -6,9 +6,9 @@ require 'rack/reloader'
 require 'rack/contrib'
 
 definition_dir = ENV.fetch('DIVER_DOWN_DIR')
-module_store = DiverDown::Web::ModuleStore.new(ENV.fetch('DIVER_DOWN_MODULE_STORE'))
+metadata = DiverDown::Web::Metadata.new(ENV.fetch('DIVER_DOWN_METADATA'))
 
 use Rack::Reloader
 use Rack::JSONBodyParser
 use DiverDown::Web::DevServerMiddleware, host: 'localhost', port: 5173 # Proxy to vite(pnpm run dev)
-run DiverDown::Web.new(definition_dir:, module_store:)
+run DiverDown::Web.new(definition_dir:, metadata:)
diff --git a/exe/diver_down_web b/exe/diver_down_web
index 1601484..b223e2b 100755
--- a/exe/diver_down_web
+++ b/exe/diver_down_web
@@ -14,7 +14,7 @@ option_parser = OptionParser.new do |opts|
     Usage: diver_down_web [options]
 
     Example:
-      diver_down_web --definition-dir /path/to/definitions --module-store /path/to/module_store.yml
+      diver_down_web --definition-dir /path/to/definitions --metadata /path/to/metadata.yml
 
     Options:
   BANNER
@@ -23,8 +23,8 @@ option_parser = OptionParser.new do |opts|
     options[:definition_dir] = path
   end
 
-  opts.on('--module-store PATH', 'Path to the module store') do |path|
-    options[:module_store] = path
+  opts.on('--metadata PATH', 'Path to the metadata.yml') do |path|
+    options[:metadata] = path
   end
 end
 option_parser.parse!(ARGV)
@@ -39,7 +39,7 @@ end
 app = Rack::JSONBodyParser.new(
   DiverDown::Web.new(
     definition_dir: options.fetch(:definition_dir),
-    module_store: DiverDown::Web::ModuleStore.new(options[:module_store] || Tempfile.new(['module_store', '.yaml']))
+    metadata: DiverDown::Web::Metadata.new(options[:metadata] || Tempfile.new(['metadata', '.yaml']).path)
   )
 )
 
diff --git a/lib/diver_down/web.rb b/lib/diver_down/web.rb
index a922eb7..585bd34 100644
--- a/lib/diver_down/web.rb
+++ b/lib/diver_down/web.rb
@@ -8,10 +8,11 @@ class Web
     WEB_DIR = File.expand_path('../../web', __dir__)
 
     require 'diver_down/web/action'
+    require 'diver_down/web/alias_store'
     require 'diver_down/web/definition_to_dot'
     require 'diver_down/web/definition_enumerator'
     require 'diver_down/web/bit_id'
-    require 'diver_down/web/module_store'
+    require 'diver_down/web/metadata'
     require 'diver_down/web/indented_string_io'
     require 'diver_down/web/definition_store'
     require 'diver_down/web/definition_loader'
@@ -20,11 +21,11 @@ class Web
     autoload :DevServerMiddleware, 'diver_down/web/dev_server_middleware'
 
     # @param definition_dir [String]
-    # @param module_store [DiverDown::ModuleStore]
+    # @param metadata [DiverDown::Web::Metadata]
     # @param store [DiverDown::Web::DefinitionStore]
-    def initialize(definition_dir:, module_store:, store: DiverDown::Web::DefinitionStore.new)
+    def initialize(definition_dir:, metadata:, store: DiverDown::Web::DefinitionStore.new)
       @store = store
-      @module_store = module_store
+      @metadata = metadata
       @files_server = Rack::Files.new(File.join(WEB_DIR))
 
       definition_files = ::Dir["#{definition_dir}/**/*.{yml,yaml,msgpack,json}"].sort
@@ -37,7 +38,7 @@ def initialize(definition_dir:, module_store:, store: DiverDown::Web::Definition
     # @return [Array[Integer, Hash, Array]]
     def call(env)
       request = Rack::Request.new(env)
-      action = DiverDown::Web::Action.new(store: @store, module_store: @module_store, request:)
+      action = DiverDown::Web::Action.new(store: @store, metadata: @metadata, request:)
 
       case [request.request_method, request.path]
       in ['GET', %r{\A/api/definitions\.json\z}]
diff --git a/lib/diver_down/web/action.rb b/lib/diver_down/web/action.rb
index 646cb60..bc6ea8f 100644
--- a/lib/diver_down/web/action.rb
+++ b/lib/diver_down/web/action.rb
@@ -13,11 +13,11 @@ class Action
       )
 
       # @param store [DiverDown::Definition::Store]
-      # @param module_store [DiverDown::Web::ModuleStore]
+      # @param metadata [DiverDown::Web::Metadata]
       # @param request [Rack::Request]
-      def initialize(store:, module_store:, request:)
+      def initialize(store:, metadata:, request:)
         @store = store
-        @module_store = module_store
+        @metadata = metadata
         @request = request
       end
 
@@ -33,14 +33,16 @@ def sources
         end
         # rubocop:enable Style/HashEachMethods
 
-        classified_sources_count = source_names.count { @module_store.classified?(_1) }
+        classified_sources_count = source_names.count { @metadata.source(_1).modules? }
 
         json(
           sources: source_names.sort.map do |source_name|
+            source = @metadata.source(source_name)
+
             {
               source_name:,
-              memo: @module_store.get_memo(source_name),
-              modules: @module_store.get_modules(source_name).map do |module_name|
+              memo: source.memo,
+              modules: source.modules.map do |module_name|
                 { module_name: }
               end,
             }
@@ -57,7 +59,7 @@ def modules
         # rubocop:disable Style/HashEachMethods
         @store.each do |_, definition|
           definition.sources.each do |source|
-            modules = @module_store.get_modules(source.source_name)
+            modules = @metadata.source(source.source_name).modules
             module_set.add(modules) unless modules.empty?
           end
         end
@@ -84,7 +86,7 @@ def module(module_names)
         # rubocop:disable Style/HashEachMethods
         @store.each do |_, definition|
           definition.sources.each do |source|
-            source_module_names = @module_store.get_modules(source.source_name)
+            source_module_names = @metadata.source(source.source_name).modules
 
             next unless source_module_names[0..module_names.size - 1] == module_names
 
@@ -109,7 +111,7 @@ def module(module_names)
           sources: source_names.sort.map do |source_name|
             {
               source_name:,
-              memo: @module_store.get_memo(source_name),
+              memo: @metadata.source(source_name).memo,
             }
           end,
           related_definitions: related_definitions.map do |definition|
@@ -139,7 +141,7 @@ def definitions(page:, per:, title:, source:, definition_group:)
               definition_group: definition.definition_group,
               title: definition.title,
               sources_count: definition.sources.size,
-              unclassified_sources_count: definition.sources.reject { @module_store.classified?(_1.source_name) }.size,
+              unclassified_sources_count: definition.sources.reject { @metadata.source(_1.source_name).modules? }.size,
             }
           end,
           pagination: pagination.to_h
@@ -187,18 +189,18 @@ def combine_definitions(bit_id, compound, concentrate, only_module)
                              end
 
         if definition
-          definition_to_dot = DiverDown::Web::DefinitionToDot.new(definition, @module_store, compound:, concentrate:, only_module:)
+          definition_to_dot = DiverDown::Web::DefinitionToDot.new(definition, @metadata, compound:, concentrate:, only_module:)
 
           json(
             titles:,
             bit_id: DiverDown::Web::BitId.ids_to_bit_id(valid_ids).to_s,
             dot: definition_to_dot.to_s,
-            dot_metadata: definition_to_dot.metadata,
+            dot_metadata: definition_to_dot.dot_metadata,
             sources: definition.sources.map do
               {
                 source_name: _1.source_name,
-                memo: @module_store.get_memo(_1.source_name),
-                modules: @module_store.get_modules(_1.source_name).map do |module_name|
+                memo: @metadata.source(_1.source_name).memo,
+                modules: @metadata.source(_1.source_name).modules.map do |module_name|
                   { module_name: }
                 end,
               }
@@ -249,12 +251,12 @@ def source(source_name)
                          []
                        else
                          source = DiverDown::Definition::Source.combine(*found_sources)
-                         @module_store.get_modules(source.source_name)
+                         @metadata.source(source.source_name).modules
                        end
 
         json(
           source_name:,
-          memo: @module_store.get_memo(source_name),
+          memo: @metadata.source(source_name).memo,
           modules: module_names.map do
             { module_name: _1 }
           end,
@@ -291,8 +293,8 @@ def set_modules(source_name, modules)
         end
 
         if found_source
-          @module_store.set_modules(source_name, modules)
-          @module_store.flush
+          @metadata.source(source_name).modules = modules
+          @metadata.flush
 
           json({})
         else
@@ -312,8 +314,8 @@ def set_memo(source_name, memo)
         end
 
         if found_source
-          @module_store.set_memo(source_name, memo)
-          @module_store.flush
+          @metadata.source(source_name).memo = memo
+          @metadata.flush
 
           json({})
         else
diff --git a/lib/diver_down/web/definition_to_dot.rb b/lib/diver_down/web/definition_to_dot.rb
index 95c1c07..d4c1ad3 100644
--- a/lib/diver_down/web/definition_to_dot.rb
+++ b/lib/diver_down/web/definition_to_dot.rb
@@ -12,8 +12,8 @@ class DefinitionToDot
       # Between modules is prominently distanced
       MODULE_MINLEN = 3
 
-      class MetadataStore
-        Metadata = Data.define(:id, :type, :data, :module_store) do
+      class DotMetadataStore
+        DotMetadata = Data.define(:id, :type, :data, :metadata) do
           # @return [Hash]
           def to_h
             case type
@@ -31,7 +31,7 @@ def to_h
           private
 
           def source_to_h
-            modules = module_store.get_modules(data.source_name).map do
+            modules = metadata.source(data.source_name).modules.map do
               {
                 module_name: _1,
               }
@@ -41,7 +41,7 @@ def source_to_h
               id:,
               type: 'source',
               source_name: data.source_name,
-              memo: module_store.get_memo(data.source_name),
+              memo: metadata.source(data.source_name).memo,
               modules:,
             }
           end
@@ -77,11 +77,11 @@ def module_to_h
           end
         end
 
-        def initialize(module_store)
+        def initialize(metadata)
           @prefix = 'graph_'
-          @module_store = module_store
+          @metadata = metadata
 
-          # Hash{ id => Metadata }
+          # Hash{ id => DotMetadata }
           @to_h = {}
         end
 
@@ -89,13 +89,13 @@ def initialize(module_store)
         # @param record [DiverDown::Definition::Source]
         # @return [String]
         def issue_source_id(source)
-          build_metadata_and_return_id(:source, source)
+          build_dot_metadata_and_return_id(:source, source)
         end
 
         # @param dependency [DiverDown::Definition::Dependency]
         # @return [String]
         def issue_dependency_id(dependency)
-          build_metadata_and_return_id(:dependency, [dependency])
+          build_dot_metadata_and_return_id(:dependency, [dependency])
         end
 
         # @param module_names [Array<String>]
@@ -106,17 +106,17 @@ def issue_modules_id(module_names)
           if issued_metadata
             issued_metadata.id
           else
-            build_metadata_and_return_id(:module, module_names)
+            build_dot_metadata_and_return_id(:module, module_names)
           end
         end
 
         # @param id [String]
         # @param dependency [DiverDown::Definition::Dependency]
         def append_dependency(id, dependency)
-          metadata = @to_h.fetch(id)
-          dependencies = metadata.data
+          dot_metadata = @to_h.fetch(id)
+          dependencies = dot_metadata.data
           combined_dependencies = DiverDown::Definition::Dependency.combine(*dependencies, dependency)
-          metadata.data.replace(combined_dependencies)
+          dot_metadata.data.replace(combined_dependencies)
         end
 
         # @return [Array<Hash>]
@@ -126,10 +126,10 @@ def to_a
 
         private
 
-        def build_metadata_and_return_id(type, data)
+        def build_dot_metadata_and_return_id(type, data)
           id = "#{@prefix}#{length + 1}"
-          metadata = Metadata.new(id:, type:, data:, module_store: @module_store)
-          @to_h[id] = metadata
+          dot_metadata = DotMetadata.new(id:, type:, data:, metadata: @metadata)
+          @to_h[id] = dot_metadata
 
           id
         end
@@ -140,24 +140,24 @@ def length
       end
 
       # @param definition [DiverDown::Definition]
-      # @param module_store [DiverDown::ModuleStore]
+      # @param metadata [DiverDown::Web::Metadata]
       # @param compound [Boolean]
       # @param concentrate [Boolean] https://graphviz.org/docs/attrs/concentrate/
-      def initialize(definition, module_store, compound: false, concentrate: false, only_module: false)
+      def initialize(definition, metadata, compound: false, concentrate: false, only_module: false)
         @definition = definition
-        @module_store = module_store
+        @metadata = metadata
         @io = DiverDown::Web::IndentedStringIo.new
         @indent = 0
         @compound = compound || only_module # When only-module is enabled, dependencies between modules are displayed as compound.
         @compound_map = Hash.new { |h, k| h[k] = {} } # Hash{ ltail => Hash{ lhead => issued id } }
         @concentrate = concentrate
         @only_module = only_module
-        @metadata_store = MetadataStore.new(module_store)
+        @dot_metadata_store = DotMetadataStore.new(metadata)
       end
 
       # @return [Array<Hash>]
-      def metadata
-        @metadata_store.to_a
+      def dot_metadata
+        @dot_metadata_store.to_a
       end
 
       # @return [String]
@@ -179,18 +179,18 @@ def to_s
 
       private
 
-      attr_reader :definition, :module_store, :io
+      attr_reader :definition, :metadata, :io
 
       def render_only_modules
         # Hash{ from_module => { to_module => Array<DiverDown::Definition::Dependency> } }
         dependency_map = Hash.new { |h, k| h[k] = Hash.new { |hi, ki| hi[ki] = [] } }
 
         definition.sources.sort_by(&:source_name).each do |source|
-          source_modules = module_store.get_modules(source.source_name)
+          source_modules = metadata.source(source.source_name).modules
           next if source_modules.empty?
 
           source.dependencies.each do |dependency|
-            dependency_modules = module_store.get_modules(dependency.source_name)
+            dependency_modules = metadata.source(dependency.source_name).modules
             next if dependency_modules.empty?
 
             dependency_map[source_modules][dependency_modules].push(dependency)
@@ -215,9 +215,9 @@ def render_only_modules
 
               io.puts %(subgraph "#{escape_quote(module_label(module_names))}" {)
               io.indented do
-                io.puts %(id="#{@metadata_store.issue_modules_id(module_names)}")
+                io.puts %(id="#{@dot_metadata_store.issue_modules_id(module_names)}")
                 io.puts %(label="#{escape_quote(module_name)}")
-                io.puts %("#{escape_quote(module_name)}" #{build_attributes(label: module_name, id: @metadata_store.issue_modules_id(module_names))})
+                io.puts %("#{escape_quote(module_name)}" #{build_attributes(label: module_name, id: @dot_metadata_store.issue_modules_id(module_names))})
 
                 next_proc&.call
               end
@@ -245,11 +245,11 @@ def render_only_modules
               # Add the dependency to the edge of the compound
               if @compound_map[ltail].include?(lhead)
                 compound_id = @compound_map[ltail][lhead]
-                @metadata_store.append_dependency(compound_id, _1)
+                @dot_metadata_store.append_dependency(compound_id, _1)
                 next
               end
 
-              compound_id = @metadata_store.issue_dependency_id(_1)
+              compound_id = @dot_metadata_store.issue_dependency_id(_1)
               @compound_map[ltail][lhead] = compound_id
 
               attributes.merge!(
@@ -269,7 +269,7 @@ def render_only_modules
 
       def render_sources
         by_modules = definition.sources.group_by do |source|
-          module_store.get_modules(source.source_name)
+          metadata.source(source.source_name).modules
         end
 
         # Remove duplicated prefix modules
@@ -297,7 +297,7 @@ def render_sources
 
                 io.puts %(subgraph "#{escape_quote(module_label(module_names))}" {)
                 io.indented do
-                  io.puts %(id="#{@metadata_store.issue_modules_id(module_names)}")
+                  io.puts %(id="#{@dot_metadata_store.issue_modules_id(module_names)}")
                   io.puts %(label="#{escape_quote(module_name)}")
 
                   sources = (by_modules[module_names] || []).sort_by(&:source_name)
@@ -321,14 +321,14 @@ def render_sources
       end
 
       def insert_source(source)
-        io.puts %("#{escape_quote(source.source_name)}" #{build_attributes(label: source.source_name, id: @metadata_store.issue_source_id(source))})
+        io.puts %("#{escape_quote(source.source_name)}" #{build_attributes(label: source.source_name, id: @dot_metadata_store.issue_source_id(source))})
       end
 
       def insert_dependencies(source)
         source.dependencies.each do
           attributes = {}
-          ltail = module_label(*module_store.get_modules(source.source_name))
-          lhead = module_label(*module_store.get_modules(_1.source_name))
+          ltail = module_label(*metadata.source(source.source_name).modules)
+          lhead = module_label(*metadata.source(_1.source_name).modules)
 
           if @compound && (ltail || lhead)
             # Rendering of dependencies between modules is done only once
@@ -338,11 +338,11 @@ def insert_dependencies(source)
             # Add the dependency to the edge of the compound
             if between_modules && @compound_map[ltail].include?(lhead)
               compound_id = @compound_map[ltail][lhead]
-              @metadata_store.append_dependency(compound_id, _1)
+              @dot_metadata_store.append_dependency(compound_id, _1)
               next
             end
 
-            compound_id = @metadata_store.issue_dependency_id(_1)
+            compound_id = @dot_metadata_store.issue_dependency_id(_1)
             @compound_map[ltail][lhead] = compound_id
 
             attributes.merge!(
@@ -353,7 +353,7 @@ def insert_dependencies(source)
             )
           else
             attributes.merge!(
-              id: @metadata_store.issue_dependency_id(_1)
+              id: @dot_metadata_store.issue_dependency_id(_1)
             )
           end
 
diff --git a/lib/diver_down/web/metadata.rb b/lib/diver_down/web/metadata.rb
new file mode 100644
index 0000000..7de52bf
--- /dev/null
+++ b/lib/diver_down/web/metadata.rb
@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+module DiverDown
+  class Web
+    class Metadata
+      require 'diver_down/web/metadata/source_metadata'
+
+      # @param path [String]
+      def initialize(path)
+        @path = path
+        load
+      end
+
+      # @param source_name [String]
+      # @return [DiverDown::Web::Metadata::SourceMetadata]
+      def source(source_name)
+        @source_map[source_name]
+      end
+
+      # @return [Hash]
+      def to_h
+        source_names = @source_map.keys.sort
+        sources = source_names.to_h { [_1, source(_1).to_h] }
+
+        {
+          sources:,
+        }
+      end
+
+      # Write store to file
+      # @return [void]
+      def flush
+        File.write(@path, to_h.to_yaml)
+      end
+
+      private
+
+      def load
+        @source_map = Hash.new { |h, source_name| h[source_name] = DiverDown::Web::Metadata::SourceMetadata.new }
+
+        begin
+          loaded = YAML.load_file(@path)
+
+          return if loaded.nil?
+
+          # NOTE: This is for backward compatibility. It will be removed in the future.
+          sources = loaded[:sources] || loaded
+
+          sources.each do |source_name, source_hash|
+            @source_map[source_name].memo = source_hash[:memo] if source_hash[:memo]
+            @source_map[source_name].modules = source_hash[:modules] if source_hash[:modules]
+          end
+        rescue StandardError
+          # Ignore error
+        end
+      end
+    end
+  end
+end
diff --git a/lib/diver_down/web/metadata/source_metadata.rb b/lib/diver_down/web/metadata/source_metadata.rb
new file mode 100644
index 0000000..3b5c61a
--- /dev/null
+++ b/lib/diver_down/web/metadata/source_metadata.rb
@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+module DiverDown
+  class Web
+    class Metadata
+      class SourceMetadata
+        BLANK_MEMO = ''
+        BLANK_RE = /\A\s*\z/
+        BLANK_ARRAY = [].freeze
+        private_constant(:BLANK_MEMO)
+        private_constant(:BLANK_RE)
+        private_constant(:BLANK_ARRAY)
+
+        attr_reader :memo, :modules
+
+        # @param source_name [String]
+        def initialize(memo: BLANK_MEMO, modules: BLANK_ARRAY)
+          @memo = memo
+          @modules = modules
+        end
+
+        # @param memo [String]
+        # @return [void]
+        def memo=(memo)
+          @memo = memo.strip
+        end
+
+        # @param module_names [Array<String>]
+        # @return [void]
+        def modules=(module_names)
+          @modules = module_names.reject do
+            BLANK_RE.match?(_1)
+          end.freeze
+        end
+
+        # @return [Boolean]
+        def modules?
+          @modules.any?
+        end
+
+        # @return [Hash]
+        def to_h
+          hash = {}
+
+          hash[:memo] = memo unless memo == BLANK_MEMO
+          hash[:modules] = modules unless modules.empty?
+
+          hash
+        end
+
+        private
+
+        def by_source_name(source_name)
+          @store[source_name] ||= {}
+        end
+      end
+    end
+  end
+end
diff --git a/lib/diver_down/web/module_store.rb b/lib/diver_down/web/module_store.rb
deleted file mode 100644
index 6875ab0..0000000
--- a/lib/diver_down/web/module_store.rb
+++ /dev/null
@@ -1,92 +0,0 @@
-# frozen_string_literal: true
-
-require 'yaml'
-
-module DiverDown
-  class Web
-    class ModuleStore
-      BLANK_ARRAY = [].freeze
-      BLANK_MEMO = ''
-      BLANK_RE = /\A\s*\z/
-
-      private_constant(:BLANK_RE)
-
-      def initialize(path)
-        @path = path
-        @store = load
-      end
-
-      # @param source_name [String]
-      # @param module_names [Array<String>]
-      def set_modules(source_name, module_names)
-        source = (@store[source_name] ||= {})
-
-        source[:modules] = module_names.dup.reject do
-          BLANK_RE.match?(_1)
-        end.freeze
-      end
-
-      # @param source_name [String]
-      # @return [Array<Module>]
-      def get_modules(source_name)
-        return BLANK_ARRAY unless @store.key?(source_name)
-
-        @store[source_name][:modules] || BLANK_ARRAY
-      end
-
-      # @param source_name [String]
-      # @param memo [String]
-      # @return [void]
-      def set_memo(source_name, memo)
-        source = (@store[source_name] ||= {})
-        source[:memo] = memo.strip
-      end
-
-      # @param source_name [String]
-      # @return [String]
-      def get_memo(source_name)
-        return BLANK_MEMO unless @store.key?(source_name)
-
-        @store[source_name][:memo] || BLANK_MEMO
-      end
-
-      # @param source_name [String]
-      # @return [Boolean]
-      def classified?(source_name)
-        get_modules(source_name).any?
-      end
-
-      # @return [Hash]
-      def to_h
-        sorted_store = {}
-
-        @store.keys.sort.each do |key|
-          sorted_store[key] = @store[key]
-        end
-
-        sorted_store
-      end
-
-      # Write store to file
-      # @return [void]
-      def flush
-        File.write(@path, to_h.to_yaml)
-      end
-
-      private
-
-      def load
-        store = {}
-
-        begin
-          loaded = YAML.load_file(@path)
-          store.merge!(loaded) if loaded
-        rescue StandardError
-          # Ignore error
-        end
-
-        store
-      end
-    end
-  end
-end
diff --git a/spec/diver_down/web/definition_to_dot_spec.rb b/spec/diver_down/web/definition_to_dot_spec.rb
index 5d5da7b..02fa5fe 100644
--- a/spec/diver_down/web/definition_to_dot_spec.rb
+++ b/spec/diver_down/web/definition_to_dot_spec.rb
@@ -11,9 +11,9 @@ def build_definition(title: 'title', sources: [])
         DiverDown::Definition.new(title:, sources: definition_sources)
       end
 
-      let(:module_store) do
+      let(:metadata) do
         path = Tempfile.new(['test', '.yaml']).path
-        DiverDown::Web::ModuleStore.new(path)
+        DiverDown::Web::Metadata.new(path)
       end
 
       context 'when definition is blank' do
@@ -22,7 +22,7 @@ def build_definition(title: 'title', sources: [])
             title: 'title'
           )
 
-          expect(described_class.new(definition, module_store).to_s).to eq(<<~DOT)
+          expect(described_class.new(definition, metadata).to_s).to eq(<<~DOT)
             strict digraph "title" {
             }
           DOT
@@ -35,7 +35,7 @@ def build_definition(title: 'title', sources: [])
             title: '"title"'
           )
 
-          expect(described_class.new(definition, module_store).to_s).to eq(<<~DOT)
+          expect(described_class.new(definition, metadata).to_s).to eq(<<~DOT)
             strict digraph "\\"title\\"" {
             }
           DOT
@@ -53,16 +53,16 @@ def build_definition(title: 'title', sources: [])
             ]
           )
 
-          module_store.set_memo('a.rb', 'memo')
+          metadata.source('a.rb').memo = 'memo'
 
-          instance = described_class.new(definition, module_store)
+          instance = described_class.new(definition, metadata)
           expect(instance.to_s).to eq(<<~DOT)
             strict digraph "title" {
               "a.rb" [label="a.rb" id="graph_1"]
             }
           DOT
 
-          expect(instance.metadata).to eq(
+          expect(instance.dot_metadata).to eq(
             [
               {
                 id: 'graph_1',
@@ -96,7 +96,7 @@ def build_definition(title: 'title', sources: [])
             ]
           )
 
-          instance = described_class.new(definition, module_store)
+          instance = described_class.new(definition, metadata)
           expect(instance.to_s).to eq(<<~DOT)
             strict digraph "title" {
               "a.rb" [label="a.rb" id="graph_1"]
@@ -105,7 +105,7 @@ def build_definition(title: 'title', sources: [])
             }
           DOT
 
-          expect(instance.metadata).to eq(
+          expect(instance.dot_metadata).to eq(
             [
               {
                 id: 'graph_1',
@@ -144,9 +144,9 @@ def build_definition(title: 'title', sources: [])
             ]
           )
 
-          module_store.set_modules('a.rb', ['A', 'B'])
+          metadata.source('a.rb').modules = ['A', 'B']
 
-          instance = described_class.new(definition, module_store)
+          instance = described_class.new(definition, metadata)
 
           expect(instance.to_s).to eq(<<~DOT)
             strict digraph "title" {
@@ -162,7 +162,7 @@ def build_definition(title: 'title', sources: [])
             }
           DOT
 
-          expect(instance.metadata).to eq(
+          expect(instance.dot_metadata).to eq(
             [
               {
                 id: 'graph_1',
@@ -216,11 +216,11 @@ def build_definition(title: 'title', sources: [])
             ]
           )
 
-          module_store.set_modules('a.rb', ['A'])
-          module_store.set_modules('b.rb', ['B'])
-          module_store.set_modules('c.rb', ['B'])
+          metadata.source('a.rb').modules = ['A']
+          metadata.source('b.rb').modules = ['B']
+          metadata.source('c.rb').modules = ['B']
 
-          instance = described_class.new(definition, module_store, compound: true)
+          instance = described_class.new(definition, metadata, compound: true)
           expect(instance.to_s).to eq(<<~DOT)
             strict digraph "title" {
               compound=true
@@ -239,7 +239,7 @@ def build_definition(title: 'title', sources: [])
             }
           DOT
 
-          expect(instance.metadata).to eq(
+          expect(instance.dot_metadata).to eq(
             [
               {
                 id: 'graph_1',
@@ -332,11 +332,11 @@ def build_definition(title: 'title', sources: [])
             ]
           )
 
-          module_store.set_modules('a.rb', ['A'])
-          module_store.set_modules('b.rb', ['B'])
-          module_store.set_modules('c.rb', ['B'])
+          metadata.source('a.rb').modules = ['A']
+          metadata.source('b.rb').modules = ['B']
+          metadata.source('c.rb').modules = ['B']
 
-          instance = described_class.new(definition, module_store, compound: true)
+          instance = described_class.new(definition, metadata, compound: true)
           expect(instance.to_s).to eq(<<~DOT)
             strict digraph "title" {
               compound=true
@@ -355,7 +355,7 @@ def build_definition(title: 'title', sources: [])
             }
           DOT
 
-          expect(instance.metadata).to eq(
+          expect(instance.dot_metadata).to eq(
             [
               {
                 id: 'graph_1',
@@ -469,13 +469,13 @@ def build_definition(title: 'title', sources: [])
             ]
           )
 
-          module_store.set_modules('a.rb', ['A'])
-          module_store.set_modules('b.rb', ['B'])
-          module_store.set_modules('c.rb', ['B'])
-          module_store.set_modules('d.rb', ['B', 'C'])
-          module_store.set_modules('unknown.rb', ['Unknown'])
+          metadata.source('a.rb').modules = ['A']
+          metadata.source('b.rb').modules = ['B']
+          metadata.source('c.rb').modules = ['B']
+          metadata.source('d.rb').modules = ['B', 'C']
+          metadata.source('unknown.rb').modules = ['Unknown']
 
-          instance = described_class.new(definition, module_store, only_module: true)
+          instance = described_class.new(definition, metadata, only_module: true)
           expect(instance.to_s).to eq(<<~DOT)
             strict digraph "title" {
               compound=true
@@ -499,7 +499,7 @@ def build_definition(title: 'title', sources: [])
             }
           DOT
 
-          expect(instance.metadata).to eq(
+          expect(instance.dot_metadata).to eq(
             [
               { id: 'graph_1', type: 'module', modules: [{ module_name: 'A' }] },
               { id: 'graph_2', type: 'module', modules: [{ module_name: 'B' }] },
@@ -536,7 +536,7 @@ def build_definition(title: 'title', sources: [])
             ]
           )
 
-          instance = described_class.new(definition, module_store, concentrate: true)
+          instance = described_class.new(definition, metadata, concentrate: true)
           expect(instance.to_s).to eq(<<~DOT)
             strict digraph "title" {
               concentrate=true
@@ -544,7 +544,7 @@ def build_definition(title: 'title', sources: [])
             }
           DOT
 
-          expect(instance.metadata).to eq(
+          expect(instance.dot_metadata).to eq(
             [
               {
                 id: 'graph_1',
@@ -575,11 +575,11 @@ def build_definition(title: 'title', sources: [])
             ]
           )
 
-          module_store.set_modules('b.rb', ['A'])
-          module_store.set_modules('c.rb', ['A', 'C'])
-          module_store.set_modules('d.rb', ['B'])
+          metadata.source('b.rb').modules = ['A']
+          metadata.source('c.rb').modules = ['A', 'C']
+          metadata.source('d.rb').modules = ['B']
 
-          instance = described_class.new(definition, module_store, concentrate: true)
+          instance = described_class.new(definition, metadata, concentrate: true)
           expect(instance.to_s).to eq(<<~DOT)
             strict digraph "title" {
               concentrate=true
@@ -602,7 +602,7 @@ def build_definition(title: 'title', sources: [])
             }
           DOT
 
-          expect(instance.metadata).to eq(
+          expect(instance.dot_metadata).to eq(
             [
               { id: 'graph_1', type: 'source', source_name: 'a.rb', memo: '', modules: [] },
               { id: 'graph_2', type: 'module', modules: [{ module_name: 'A' }] },
diff --git a/spec/diver_down/web/metadata/source_metadata_spec.rb b/spec/diver_down/web/metadata/source_metadata_spec.rb
new file mode 100644
index 0000000..41ce0d9
--- /dev/null
+++ b/spec/diver_down/web/metadata/source_metadata_spec.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+RSpec.describe DiverDown::Web::Metadata::SourceMetadata do
+  describe 'InstanceMethods' do
+    describe '#memo/#memo=' do
+      it 'read/write memo' do
+        instance = described_class.new
+
+        expect {
+          instance.memo = 'memo'
+        }.to change {
+          instance.memo
+        }.from('').to('memo')
+      end
+    end
+
+    describe '#modules/modules=' do
+      it 'read/write modules' do
+        instance = described_class.new
+
+        expect {
+          instance.modules = ['A', 'B']
+        }.to change {
+          instance.modules
+        }.from([]).to(['A', 'B'])
+      end
+    end
+
+    describe '#modules?' do
+      it 'returns bool' do
+        instance = described_class.new
+
+        expect {
+          instance.modules = ['A', 'B']
+        }.to change {
+          instance.modules?
+        }.from(false).to(true)
+      end
+    end
+
+    describe '#to_h' do
+      it 'returns hash' do
+        instance = described_class.new
+        expect(instance.to_h).to eq({})
+
+        instance.memo = 'a'
+        instance.modules = ['A']
+
+        expect(instance.to_h).to eq({ memo: 'a', modules: ['A'] })
+      end
+    end
+  end
+end
diff --git a/spec/diver_down/web/metadata_spec.rb b/spec/diver_down/web/metadata_spec.rb
new file mode 100644
index 0000000..3542e3f
--- /dev/null
+++ b/spec/diver_down/web/metadata_spec.rb
@@ -0,0 +1,88 @@
+# frozen_string_literal: true
+
+RSpec.describe DiverDown::Web::Metadata do
+  describe 'InstanceMethods' do
+    def build_temp_path
+      Tempfile.new(['test', '.yaml']).path
+    end
+
+    describe '#load' do
+      it "does not raise error if file doesn't exist" do
+        path = build_temp_path
+        expect { described_class.new(path) }.to_not raise_error
+      end
+    end
+
+    describe '#source' do
+      it 'returns DiverDown::Web::Metadata::SourceMetadata' do
+        path = build_temp_path
+        instance = described_class.new(path)
+
+        source_a = instance.source('a.rb')
+        source_b = instance.source('b.rb')
+        expect(source_a).to be_a(DiverDown::Web::Metadata::SourceMetadata)
+        expect(source_b).to be_a(DiverDown::Web::Metadata::SourceMetadata)
+      end
+    end
+
+    describe '#flush' do
+      it 'writes modules to path' do
+        tempfile = Tempfile.new(['test', '.yaml'])
+        instance = described_class.new(tempfile.path)
+        instance.source('a.rb').modules = ['A', 'B']
+
+        expect {
+          instance.flush
+        }.to change {
+          described_class.new(tempfile.path).source('a.rb').modules
+        }.from([]).to(['A', 'B'])
+      end
+
+      it 'writes memo to path' do
+        tempfile = Tempfile.new(['test', '.yaml'])
+        instance = described_class.new(tempfile.path)
+        instance.source('a.rb').memo = 'memo'
+
+        expect {
+          instance.flush
+        }.to change {
+          described_class.new(tempfile.path).source('a.rb').memo
+        }.from('').to('memo')
+      end
+
+      it 'sorts by source name' do
+        tempfile = Tempfile.new(['test', '.yaml'])
+        instance = described_class.new(tempfile.path)
+
+        sources = ['a.rb', 'b.rb', 'c.rb']
+
+        sources.shuffle.each do |source|
+          instance.source(source).modules = ['A']
+        end
+
+        expect {
+          instance.flush
+        }.to change {
+          described_class.new(tempfile.path).instance_variable_get(:@source_map).keys
+        }.from([]).to(sources)
+      end
+    end
+
+    describe '#to_h' do
+      it 'returns sorted hash' do
+        tempfile = Tempfile.new(['test', '.yaml'])
+        instance = described_class.new(tempfile.path)
+
+        source_names = ['a.rb', 'b.rb', 'c.rb']
+
+        source_names.shuffle.each do |source_name|
+          source = instance.source(source_name)
+          source.modules = ['A']
+          source.memo = 'memo'
+        end
+
+        expect(instance.to_h[:sources].keys).to eq(source_names)
+      end
+    end
+  end
+end
diff --git a/spec/diver_down/web/module_store_spec.rb b/spec/diver_down/web/module_store_spec.rb
deleted file mode 100644
index e9918b1..0000000
--- a/spec/diver_down/web/module_store_spec.rb
+++ /dev/null
@@ -1,135 +0,0 @@
-# frozen_string_literal: true
-
-RSpec.describe DiverDown::Web::ModuleStore do
-  describe 'InstanceMethods' do
-    describe '#initialize' do
-      it "does not raise error if file doesn't exist" do
-        path = "#{Dir.tmpdir}/not_exist.yaml"
-        expect { described_class.new(path) }.to_not raise_error
-      end
-    end
-
-    describe '#set_modules' do
-      it 'set_modules modules to source' do
-        tempfile = Tempfile.new(['test', '.yaml'])
-        instance = described_class.new(tempfile.path)
-
-        expect {
-          instance.set_modules('a.rb', ['A', 'B'])
-        }.to change {
-          instance.get_modules('a.rb')
-        }.from([]).to(['A', 'B'])
-      end
-    end
-
-    describe '#get_modules' do
-      it 'returns blank array if source is not set_modules' do
-        tempfile = Tempfile.new(['test', '.yaml'])
-        instance = described_class.new(tempfile.path)
-
-        expect(instance.get_modules('a.rb')).to eq([])
-
-        instance.set_modules('a.rb', ['A', 'B'])
-        expect(instance.get_modules('a.rb')).to eq(['A', 'B'])
-      end
-    end
-
-    describe '#set_memo' do
-      it 'sets memo' do
-        tempfile = Tempfile.new(['test', '.yaml'])
-        instance = described_class.new(tempfile.path)
-
-        expect {
-          instance.set_memo('a.rb', ' memo ')
-        }.to change {
-          instance.get_memo('a.rb')
-        }.from('').to('memo')
-      end
-    end
-
-    describe '#get_memo' do
-      it 'returns blank string if source is not set_modules' do
-        tempfile = Tempfile.new(['test', '.yaml'])
-        instance = described_class.new(tempfile.path)
-
-        expect(instance.get_memo('a.rb')).to eq('')
-
-        instance.set_memo('a.rb', 'a')
-        expect(instance.get_memo('a.rb')).to eq('a')
-      end
-    end
-
-    describe '#classified?' do
-      it 'returns bool' do
-        tempfile = Tempfile.new(['test', '.yaml'])
-        instance = described_class.new(tempfile.path)
-
-        instance.set_modules('a.rb', [])
-        instance.set_modules('b.rb', ['A'])
-
-        expect(instance.classified?('a.rb')).to be(false)
-        expect(instance.classified?('b.rb')).to be(true)
-        expect(instance.classified?('c.rb')).to be(false)
-      end
-    end
-
-    describe '#flush' do
-      it 'writes modules to path' do
-        tempfile = Tempfile.new(['test', '.yaml'])
-        instance = described_class.new(tempfile.path)
-        instance.set_modules('a.rb', ['A', 'B'])
-
-        expect {
-          instance.flush
-        }.to change {
-          described_class.new(tempfile.path).get_modules('a.rb')
-        }.from([]).to(['A', 'B'])
-      end
-
-      it 'writes memo to path' do
-        tempfile = Tempfile.new(['test', '.yaml'])
-        instance = described_class.new(tempfile.path)
-        instance.set_memo('a.rb', 'memo')
-
-        expect {
-          instance.flush
-        }.to change {
-          described_class.new(tempfile.path).get_memo('a.rb')
-        }.from('').to('memo')
-      end
-
-      it 'sorts by source name' do
-        tempfile = Tempfile.new(['test', '.yaml'])
-        instance = described_class.new(tempfile.path)
-
-        sources = ['a.rb', 'b.rb', 'c.rb']
-
-        sources.shuffle.each do |source|
-          instance.set_modules(source, ['A'])
-        end
-
-        expect {
-          instance.flush
-        }.to change {
-          described_class.new(tempfile.path).instance_variable_get(:@store).keys
-        }.from([]).to(sources)
-      end
-    end
-
-    describe '#to_h' do
-      it 'returns sorted hash' do
-        tempfile = Tempfile.new(['test', '.yaml'])
-        instance = described_class.new(tempfile.path)
-
-        sources = ['a.rb', 'b.rb', 'c.rb']
-
-        sources.shuffle.each do |source|
-          instance.set_modules(source, ['A'])
-          instance.set_memo(source, 'memo')
-        end
-
-        expect(instance.to_h.keys).to eq(sources)
-      end
-    end
-  end
-end
diff --git a/spec/diver_down/web_spec.rb b/spec/diver_down/web_spec.rb
index 24084f0..7b54f22 100644
--- a/spec/diver_down/web_spec.rb
+++ b/spec/diver_down/web_spec.rb
@@ -4,7 +4,7 @@
   include Rack::Test::Methods
 
   def app
-    @app ||= described_class.new(definition_dir:, module_store:, store:)
+    @app ||= described_class.new(definition_dir:, metadata:, store:)
   end
 
   let(:definition_dir) do
@@ -15,9 +15,9 @@ def app
     DiverDown::Web::DefinitionStore.new
   end
 
-  let(:module_store) do
-    module_store_path = Tempfile.new(['test', '.yaml']).path
-    DiverDown::Web::ModuleStore.new(module_store_path)
+  let(:metadata) do
+    metadata_path = Tempfile.new(['test', '.yaml']).path
+    DiverDown::Web::Metadata.new(metadata_path)
   end
 
   describe 'GET /' do
@@ -76,7 +76,7 @@ def app
         ]
       )
       store.set(definition_1, definition_2)
-      module_store.set_modules('a.rb', ['A'])
+      metadata.source('a.rb').modules = ['A']
 
       get '/api/definitions.json'
 
@@ -315,8 +315,8 @@ def assert_definition_group(definition_group, expected_ids)
       )
       store.set(definition)
 
-      module_store.set_modules('a.rb', ['A'])
-      module_store.set_memo('a.rb', 'memo')
+      metadata.source('a.rb').modules = ['A']
+      metadata.source('a.rb').memo = 'memo'
 
       get '/api/sources.json'
 
@@ -370,8 +370,8 @@ def assert_definition_group(definition_group, expected_ids)
         ]
       )
       store.set(definition)
-      module_store.set_modules('a.rb', ['A', 'B'])
-      module_store.set_modules('b.rb', ['B', 'C'])
+      metadata.source('a.rb').modules = ['A', 'B']
+      metadata.source('b.rb').modules = ['B', 'C']
 
       get '/api/modules.json'
 
@@ -422,9 +422,9 @@ def assert_definition_group(definition_group, expected_ids)
       )
 
       ids = store.set(definition_1, definition_2)
-      module_store.set_modules('a.rb', ['A'])
-      module_store.set_modules('b.rb', ['A', 'B'])
-      module_store.set_memo('a.rb', 'memo')
+      metadata.source('a.rb').modules = ['A']
+      metadata.source('b.rb').modules = ['A', 'B']
+      metadata.source('a.rb').memo = 'memo'
 
       get '/api/modules/A.json'
 
@@ -494,8 +494,8 @@ def assert_definition_group(definition_group, expected_ids)
       )
 
       ids = store.set(definition)
-      module_store.set_modules('a.rb', ['グローバル'])
-      module_store.set_memo('a.rb', 'memo')
+      metadata.source('a.rb').modules = ['グローバル']
+      metadata.source('a.rb').memo = 'memo'
 
       get "/api/modules/#{CGI.escape('グローバル')}.json"
 
@@ -565,7 +565,7 @@ def assert_definition_group(definition_group, expected_ids)
       )
       bit_ids = store.set(definition_1, definition_2)
 
-      module_store.set_memo('a.rb', 'memo')
+      metadata.source('a.rb').memo = 'memo'
 
       get "/api/definitions/#{bit_ids.inject(0, &:|)}.json"
 
@@ -637,7 +637,7 @@ def assert_definition_group(definition_group, expected_ids)
       store.set(definition_1)
       store.set(definition_2)
 
-      module_store.set_memo('a.rb', 'memo')
+      metadata.source('a.rb').memo = 'memo'
 
       get '/api/sources/a.rb.json'
 
@@ -681,7 +681,7 @@ def assert_definition_group(definition_group, expected_ids)
 
       expect(last_response.status).to eq(200)
 
-      expect(module_store.get_modules('a.rb')).to eq(['A', 'B'])
+      expect(metadata.source('a.rb').modules).to eq(['A', 'B'])
     end
 
     it 'ignores blank modules' do
@@ -699,7 +699,7 @@ def assert_definition_group(definition_group, expected_ids)
 
       expect(last_response.status).to eq(200)
 
-      expect(module_store.get_modules('a.rb')).to eq(['B'])
+      expect(metadata.source('a.rb').modules).to eq(['B'])
     end
   end
 
@@ -725,7 +725,7 @@ def assert_definition_group(definition_group, expected_ids)
 
       expect(last_response.status).to eq(200)
 
-      expect(module_store.get_memo('a.rb')).to eq('memo')
+      expect(metadata.source('a.rb').memo).to eq('memo')
     end
   end
 end