diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c6d2861..b792729 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -44,7 +44,7 @@ jobs:
         id: npm-ci-test
         run: npm run ci-test
 
-  test-action:
+  create-slack-message:
     name: GitHub Actions Test
     runs-on: ubuntu-latest
 
@@ -53,12 +53,10 @@ jobs:
         id: checkout
         uses: actions/checkout@v4
 
-      - name: Test Local Action
-        id: test-action
+      - name: Create message for Slack posts
+        id: create-message
         uses: ./
-        with:
-          milliseconds: 2000
 
       - name: Print Output
         id: output
-        run: echo "${{ steps.test-action.outputs.time }}"
+        run: echo "${{ steps.create-message.outputs.message }}"
diff --git a/__tests__/main.test.ts b/__tests__/main.test.ts
index ce373fb..5fa5f5f 100644
--- a/__tests__/main.test.ts
+++ b/__tests__/main.test.ts
@@ -7,13 +7,10 @@
  */
 
 import * as core from '@actions/core'
-import * as main from '../src/main'
+// import * as main from '../src/main'
 
 // Mock the action's main function
-const runMock = jest.spyOn(main, 'run')
-
-// Other utilities
-const timeRegex = /^\d{2}:\d{2}:\d{2}/
+// const runMock = jest.spyOn(main, 'run')
 
 // Mock the GitHub Actions core library
 let debugMock: jest.SpiedFunction<typeof core.debug>
@@ -22,7 +19,7 @@ let getInputMock: jest.SpiedFunction<typeof core.getInput>
 let setFailedMock: jest.SpiedFunction<typeof core.setFailed>
 let setOutputMock: jest.SpiedFunction<typeof core.setOutput>
 
-describe('action', () => {
+describe.skip('action', () => {
   beforeEach(() => {
     jest.clearAllMocks()
 
@@ -32,58 +29,4 @@ describe('action', () => {
     setFailedMock = jest.spyOn(core, 'setFailed').mockImplementation()
     setOutputMock = jest.spyOn(core, 'setOutput').mockImplementation()
   })
-
-  it('sets the time output', async () => {
-    // Set the action's inputs as return values from core.getInput()
-    getInputMock.mockImplementation(name => {
-      switch (name) {
-        case 'milliseconds':
-          return '500'
-        default:
-          return ''
-      }
-    })
-
-    await main.run()
-    expect(runMock).toHaveReturned()
-
-    // Verify that all of the core library functions were called correctly
-    expect(debugMock).toHaveBeenNthCalledWith(1, 'Waiting 500 milliseconds ...')
-    expect(debugMock).toHaveBeenNthCalledWith(
-      2,
-      expect.stringMatching(timeRegex)
-    )
-    expect(debugMock).toHaveBeenNthCalledWith(
-      3,
-      expect.stringMatching(timeRegex)
-    )
-    expect(setOutputMock).toHaveBeenNthCalledWith(
-      1,
-      'time',
-      expect.stringMatching(timeRegex)
-    )
-    expect(errorMock).not.toHaveBeenCalled()
-  })
-
-  it('sets a failed status', async () => {
-    // Set the action's inputs as return values from core.getInput()
-    getInputMock.mockImplementation(name => {
-      switch (name) {
-        case 'milliseconds':
-          return 'this is not a number'
-        default:
-          return ''
-      }
-    })
-
-    await main.run()
-    expect(runMock).toHaveReturned()
-
-    // Verify that all of the core library functions were called correctly
-    expect(setFailedMock).toHaveBeenNthCalledWith(
-      1,
-      'milliseconds not a number'
-    )
-    expect(errorMock).not.toHaveBeenCalled()
-  })
 })
diff --git a/__tests__/wait.test.ts b/__tests__/wait.test.ts
deleted file mode 100644
index 1336aaa..0000000
--- a/__tests__/wait.test.ts
+++ /dev/null
@@ -1,25 +0,0 @@
-/**
- * Unit tests for src/wait.ts
- */
-
-import { wait } from '../src/wait'
-import { expect } from '@jest/globals'
-
-describe('wait.ts', () => {
-  it('throws an invalid number', async () => {
-    const input = parseInt('foo', 10)
-    expect(isNaN(input)).toBe(true)
-
-    await expect(wait(input)).rejects.toThrow('milliseconds not a number')
-  })
-
-  it('waits with a valid number', async () => {
-    const start = new Date()
-    await wait(500)
-    const end = new Date()
-
-    const delta = Math.abs(end.getTime() - start.getTime())
-
-    expect(delta).toBeGreaterThan(450)
-  })
-})
diff --git a/action.yml b/action.yml
index 101186a..9f13ad0 100644
--- a/action.yml
+++ b/action.yml
@@ -1,11 +1,7 @@
-name: 'The name of your action here'
-description: 'Provide a description here'
-author: 'Your name or organization here'
-
-# Add your action's branding here. This will appear on the GitHub Marketplace.
-branding:
-  icon: 'heart'
-  color: 'red'
+name: 'GitHub notice to Slack'
+description:
+  'This workflow is triggered by the opening of a pull request and notifies
+  users assigned as reviewers via mention on Slack.'
 
 # Define your inputs here.
 inputs:
diff --git a/package-lock.json b/package-lock.json
index 27da3b7..4ba3d14 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9,10 +9,12 @@
       "version": "0.0.0",
       "license": "MIT",
       "dependencies": {
-        "@actions/core": "^1.10.1"
+        "@actions/core": "^1.10.1",
+        "@actions/github": "^6.0.0"
       },
       "devDependencies": {
         "@jest/globals": "^29.7.0",
+        "@octokit/webhooks-types": "^7.5.1",
         "@types/jest": "^29.5.13",
         "@types/node": "^22.5.5",
         "@typescript-eslint/eslint-plugin": "^8.6.0",
@@ -51,6 +53,17 @@
         "uuid": "^8.3.2"
       }
     },
+    "node_modules/@actions/github": {
+      "version": "6.0.0",
+      "resolved": "https://registry.npmjs.org/@actions/github/-/github-6.0.0.tgz",
+      "integrity": "sha512-alScpSVnYmjNEXboZjarjukQEzgCRmjMv6Xj47fsdnqGS73bjJNDpiiXmp8jr0UZLdUB6d9jW63IcmddUP+l0g==",
+      "dependencies": {
+        "@actions/http-client": "^2.2.0",
+        "@octokit/core": "^5.0.1",
+        "@octokit/plugin-paginate-rest": "^9.0.0",
+        "@octokit/plugin-rest-endpoint-methods": "^10.0.0"
+      }
+    },
     "node_modules/@actions/http-client": {
       "version": "2.2.0",
       "resolved": "https://registry.npmjs.org/@actions/http-client/-/http-client-2.2.0.tgz",
@@ -1332,6 +1345,156 @@
         "node": ">= 8"
       }
     },
+    "node_modules/@octokit/auth-token": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/@octokit/auth-token/-/auth-token-4.0.0.tgz",
+      "integrity": "sha512-tY/msAuJo6ARbK6SPIxZrPBms3xPbfwBrulZe0Wtr/DIY9lje2HeV1uoebShn6mx7SjCHif6EjMvoREj+gZ+SA==",
+      "engines": {
+        "node": ">= 18"
+      }
+    },
+    "node_modules/@octokit/core": {
+      "version": "5.2.0",
+      "resolved": "https://registry.npmjs.org/@octokit/core/-/core-5.2.0.tgz",
+      "integrity": "sha512-1LFfa/qnMQvEOAdzlQymH0ulepxbxnCYAKJZfMci/5XJyIHWgEYnDmgnKakbTh7CH2tFQ5O60oYDvns4i9RAIg==",
+      "dependencies": {
+        "@octokit/auth-token": "^4.0.0",
+        "@octokit/graphql": "^7.1.0",
+        "@octokit/request": "^8.3.1",
+        "@octokit/request-error": "^5.1.0",
+        "@octokit/types": "^13.0.0",
+        "before-after-hook": "^2.2.0",
+        "universal-user-agent": "^6.0.0"
+      },
+      "engines": {
+        "node": ">= 18"
+      }
+    },
+    "node_modules/@octokit/endpoint": {
+      "version": "9.0.5",
+      "resolved": "https://registry.npmjs.org/@octokit/endpoint/-/endpoint-9.0.5.tgz",
+      "integrity": "sha512-ekqR4/+PCLkEBF6qgj8WqJfvDq65RH85OAgrtnVp1mSxaXF03u2xW/hUdweGS5654IlC0wkNYC18Z50tSYTAFw==",
+      "dependencies": {
+        "@octokit/types": "^13.1.0",
+        "universal-user-agent": "^6.0.0"
+      },
+      "engines": {
+        "node": ">= 18"
+      }
+    },
+    "node_modules/@octokit/graphql": {
+      "version": "7.1.0",
+      "resolved": "https://registry.npmjs.org/@octokit/graphql/-/graphql-7.1.0.tgz",
+      "integrity": "sha512-r+oZUH7aMFui1ypZnAvZmn0KSqAUgE1/tUXIWaqUCa1758ts/Jio84GZuzsvUkme98kv0WFY8//n0J1Z+vsIsQ==",
+      "dependencies": {
+        "@octokit/request": "^8.3.0",
+        "@octokit/types": "^13.0.0",
+        "universal-user-agent": "^6.0.0"
+      },
+      "engines": {
+        "node": ">= 18"
+      }
+    },
+    "node_modules/@octokit/openapi-types": {
+      "version": "22.2.0",
+      "resolved": "https://registry.npmjs.org/@octokit/openapi-types/-/openapi-types-22.2.0.tgz",
+      "integrity": "sha512-QBhVjcUa9W7Wwhm6DBFu6ZZ+1/t/oYxqc2tp81Pi41YNuJinbFRx8B133qVOrAaBbF7D/m0Et6f9/pZt9Rc+tg=="
+    },
+    "node_modules/@octokit/plugin-paginate-rest": {
+      "version": "9.2.1",
+      "resolved": "https://registry.npmjs.org/@octokit/plugin-paginate-rest/-/plugin-paginate-rest-9.2.1.tgz",
+      "integrity": "sha512-wfGhE/TAkXZRLjksFXuDZdmGnJQHvtU/joFQdweXUgzo1XwvBCD4o4+75NtFfjfLK5IwLf9vHTfSiU3sLRYpRw==",
+      "dependencies": {
+        "@octokit/types": "^12.6.0"
+      },
+      "engines": {
+        "node": ">= 18"
+      },
+      "peerDependencies": {
+        "@octokit/core": "5"
+      }
+    },
+    "node_modules/@octokit/plugin-paginate-rest/node_modules/@octokit/openapi-types": {
+      "version": "20.0.0",
+      "resolved": "https://registry.npmjs.org/@octokit/openapi-types/-/openapi-types-20.0.0.tgz",
+      "integrity": "sha512-EtqRBEjp1dL/15V7WiX5LJMIxxkdiGJnabzYx5Apx4FkQIFgAfKumXeYAqqJCj1s+BMX4cPFIFC4OLCR6stlnA=="
+    },
+    "node_modules/@octokit/plugin-paginate-rest/node_modules/@octokit/types": {
+      "version": "12.6.0",
+      "resolved": "https://registry.npmjs.org/@octokit/types/-/types-12.6.0.tgz",
+      "integrity": "sha512-1rhSOfRa6H9w4YwK0yrf5faDaDTb+yLyBUKOCV4xtCDB5VmIPqd/v9yr9o6SAzOAlRxMiRiCic6JVM1/kunVkw==",
+      "dependencies": {
+        "@octokit/openapi-types": "^20.0.0"
+      }
+    },
+    "node_modules/@octokit/plugin-rest-endpoint-methods": {
+      "version": "10.4.1",
+      "resolved": "https://registry.npmjs.org/@octokit/plugin-rest-endpoint-methods/-/plugin-rest-endpoint-methods-10.4.1.tgz",
+      "integrity": "sha512-xV1b+ceKV9KytQe3zCVqjg+8GTGfDYwaT1ATU5isiUyVtlVAO3HNdzpS4sr4GBx4hxQ46s7ITtZrAsxG22+rVg==",
+      "dependencies": {
+        "@octokit/types": "^12.6.0"
+      },
+      "engines": {
+        "node": ">= 18"
+      },
+      "peerDependencies": {
+        "@octokit/core": "5"
+      }
+    },
+    "node_modules/@octokit/plugin-rest-endpoint-methods/node_modules/@octokit/openapi-types": {
+      "version": "20.0.0",
+      "resolved": "https://registry.npmjs.org/@octokit/openapi-types/-/openapi-types-20.0.0.tgz",
+      "integrity": "sha512-EtqRBEjp1dL/15V7WiX5LJMIxxkdiGJnabzYx5Apx4FkQIFgAfKumXeYAqqJCj1s+BMX4cPFIFC4OLCR6stlnA=="
+    },
+    "node_modules/@octokit/plugin-rest-endpoint-methods/node_modules/@octokit/types": {
+      "version": "12.6.0",
+      "resolved": "https://registry.npmjs.org/@octokit/types/-/types-12.6.0.tgz",
+      "integrity": "sha512-1rhSOfRa6H9w4YwK0yrf5faDaDTb+yLyBUKOCV4xtCDB5VmIPqd/v9yr9o6SAzOAlRxMiRiCic6JVM1/kunVkw==",
+      "dependencies": {
+        "@octokit/openapi-types": "^20.0.0"
+      }
+    },
+    "node_modules/@octokit/request": {
+      "version": "8.4.0",
+      "resolved": "https://registry.npmjs.org/@octokit/request/-/request-8.4.0.tgz",
+      "integrity": "sha512-9Bb014e+m2TgBeEJGEbdplMVWwPmL1FPtggHQRkV+WVsMggPtEkLKPlcVYm/o8xKLkpJ7B+6N8WfQMtDLX2Dpw==",
+      "dependencies": {
+        "@octokit/endpoint": "^9.0.1",
+        "@octokit/request-error": "^5.1.0",
+        "@octokit/types": "^13.1.0",
+        "universal-user-agent": "^6.0.0"
+      },
+      "engines": {
+        "node": ">= 18"
+      }
+    },
+    "node_modules/@octokit/request-error": {
+      "version": "5.1.0",
+      "resolved": "https://registry.npmjs.org/@octokit/request-error/-/request-error-5.1.0.tgz",
+      "integrity": "sha512-GETXfE05J0+7H2STzekpKObFe765O5dlAKUTLNGeH+x47z7JjXHfsHKo5z21D/o/IOZTUEI6nyWyR+bZVP/n5Q==",
+      "dependencies": {
+        "@octokit/types": "^13.1.0",
+        "deprecation": "^2.0.0",
+        "once": "^1.4.0"
+      },
+      "engines": {
+        "node": ">= 18"
+      }
+    },
+    "node_modules/@octokit/types": {
+      "version": "13.6.0",
+      "resolved": "https://registry.npmjs.org/@octokit/types/-/types-13.6.0.tgz",
+      "integrity": "sha512-CrooV/vKCXqwLa+osmHLIMUb87brpgUqlqkPGc6iE2wCkUvTrHiXFMhAKoDDaAAYJrtKtrFTgSQTg5nObBEaew==",
+      "dependencies": {
+        "@octokit/openapi-types": "^22.2.0"
+      }
+    },
+    "node_modules/@octokit/webhooks-types": {
+      "version": "7.5.1",
+      "resolved": "https://registry.npmjs.org/@octokit/webhooks-types/-/webhooks-types-7.5.1.tgz",
+      "integrity": "sha512-1dozxWEP8lKGbtEu7HkRbK1F/nIPuJXNfT0gd96y6d3LcHZTtRtlf8xz3nicSJfesADxJyDh+mWBOsdLkqgzYw==",
+      "dev": true
+    },
     "node_modules/@pkgr/core": {
       "version": "0.1.1",
       "resolved": "https://registry.npmjs.org/@pkgr/core/-/core-0.1.1.tgz",
@@ -1938,6 +2101,11 @@
       "integrity": "sha512-3oSeUO0TMV67hN1AmbXsK4yaqU7tjiHlbxRDZOpH0KW9+CeX4bRAaX0Anxt0tx2MrpRpWwQaPwIlISEJhYU5Pw==",
       "dev": true
     },
+    "node_modules/before-after-hook": {
+      "version": "2.2.3",
+      "resolved": "https://registry.npmjs.org/before-after-hook/-/before-after-hook-2.2.3.tgz",
+      "integrity": "sha512-NzUnlZexiaH/46WDhANlyR2bXRopNg4F/zuSA3OpZnllCUgRaOF2znDioDWrmbNVsuZk6l9pMquQB38cfBZwkQ=="
+    },
     "node_modules/brace-expansion": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-2.0.1.tgz",
@@ -2252,6 +2420,11 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/deprecation": {
+      "version": "2.3.1",
+      "resolved": "https://registry.npmjs.org/deprecation/-/deprecation-2.3.1.tgz",
+      "integrity": "sha512-xmHIy4F3scKVwMsQ4WnVaS8bHOx0DmVwRywosKhaILI0ywMDWPtBSku2HNxRvF7jtwDRsoEwYQSfbxj8b7RlJQ=="
+    },
     "node_modules/detect-newline": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/detect-newline/-/detect-newline-3.1.0.tgz",
@@ -4336,7 +4509,6 @@
       "version": "1.4.0",
       "resolved": "https://registry.npmjs.org/once/-/once-1.4.0.tgz",
       "integrity": "sha512-lNaJgI+2Q5URQBkccEKHTQOPaXdUxnZZElQTZY0MFUAuaEqe1E+Nyvgdz/aIyNi6Z9MzO5dv1H8n58/GELp3+w==",
-      "dev": true,
       "dependencies": {
         "wrappy": "1"
       }
@@ -5375,6 +5547,11 @@
       "integrity": "sha512-e/vggGopEfTKSvj4ihnOLTsqhrKRN3LeO6qSN/GxohhuRv8qH9bNQ4B8W7e/vFL+0XTnmHPB4/kegunZGA4Org==",
       "dev": true
     },
+    "node_modules/universal-user-agent": {
+      "version": "6.0.1",
+      "resolved": "https://registry.npmjs.org/universal-user-agent/-/universal-user-agent-6.0.1.tgz",
+      "integrity": "sha512-yCzhz6FN2wU1NiiQRogkTQszlQSlpWaw8SvVegAc+bDxbzHgh1vX8uIe8OYyMH6DwH+sdTJsgMl36+mSMdRJIQ=="
+    },
     "node_modules/update-browserslist-db": {
       "version": "1.0.13",
       "resolved": "https://registry.npmjs.org/update-browserslist-db/-/update-browserslist-db-1.0.13.tgz",
@@ -5504,8 +5681,7 @@
     "node_modules/wrappy": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz",
-      "integrity": "sha512-l4Sp/DRseor9wL6EvV2+TuQn63dMkPjZ/sp9XkghTEbV9KlPS1xUsZ3u7/IQO4wxtcFB4bgpQPRcR3QCvezPcQ==",
-      "dev": true
+      "integrity": "sha512-l4Sp/DRseor9wL6EvV2+TuQn63dMkPjZ/sp9XkghTEbV9KlPS1xUsZ3u7/IQO4wxtcFB4bgpQPRcR3QCvezPcQ=="
     },
     "node_modules/write-file-atomic": {
       "version": "4.0.2",
diff --git a/package.json b/package.json
index 1d8854a..9c13120 100644
--- a/package.json
+++ b/package.json
@@ -66,10 +66,12 @@
     ]
   },
   "dependencies": {
-    "@actions/core": "^1.10.1"
+    "@actions/core": "^1.10.1",
+    "@actions/github": "^6.0.0"
   },
   "devDependencies": {
     "@jest/globals": "^29.7.0",
+    "@octokit/webhooks-types": "^7.5.1",
     "@types/jest": "^29.5.13",
     "@types/node": "^22.5.5",
     "@typescript-eslint/eslint-plugin": "^8.6.0",
diff --git a/src/create-context.ts b/src/create-context.ts
new file mode 100644
index 0000000..7730f75
--- /dev/null
+++ b/src/create-context.ts
@@ -0,0 +1,47 @@
+import { PullRequestEvent } from '@octokit/webhooks-types'
+import { toSlackUser } from './to-slack-user'
+
+interface ImageElement {
+  type: 'image'
+  image_url: string
+  alt_text: string
+}
+
+interface TextElement {
+  type: 'mrkdwn'
+  text: string
+}
+
+export interface Context {
+  type: 'context'
+  elements: (ImageElement | TextElement)[]
+}
+
+// createContext is like a Footer, show PR creator and repository name
+export function createContext(payload: PullRequestEvent): Context {
+  const {
+    pull_request: { user },
+    repository: { full_name }
+  } = payload
+
+  const creator = toSlackUser(user.login)
+
+  const contextText = `${creator} - :github: ${full_name}`
+
+  const context: Context = {
+    type: 'context',
+    elements: [
+      {
+        type: 'image',
+        image_url: user.avatar_url,
+        alt_text: user.login
+      },
+      {
+        type: 'mrkdwn',
+        text: contextText
+      }
+    ]
+  }
+
+  return context
+}
diff --git a/src/create-section.ts b/src/create-section.ts
new file mode 100644
index 0000000..0571389
--- /dev/null
+++ b/src/create-section.ts
@@ -0,0 +1,31 @@
+import { PullRequestEvent } from '@octokit/webhooks-types'
+import { toSlackUsers } from './to-slack-users'
+
+export interface Section {
+  type: 'section'
+  text: {
+    type: 'mrkdwn'
+    text: string
+  }
+}
+
+// createSectionでメッセージの本文を作成。レビュアーの一覧とPRタイトルのリンクが表示される。
+// toSlackUsersは Record<GithubAccountName, SlackAccountName> をハードコードで管理していて、Githubのアカウント名からSlackのメンションを作成している
+export function createSection(payload: PullRequestEvent): Section {
+  const {
+    pull_request: { title, html_url, number, requested_reviewers }
+  } = payload
+
+  const reviewers = toSlackUsers(requested_reviewers)
+
+  const sectionText = `${reviewers.join(' ')}\n*<${html_url}|#${number} - ${title}>*`
+  const section: Section = {
+    type: 'section',
+    text: {
+      type: 'mrkdwn',
+      text: sectionText
+    }
+  }
+
+  return section
+}
diff --git a/src/create-slack-message.ts b/src/create-slack-message.ts
new file mode 100644
index 0000000..c7798b6
--- /dev/null
+++ b/src/create-slack-message.ts
@@ -0,0 +1,28 @@
+import * as core from '@actions/core'
+import * as github from '@actions/github'
+import { PullRequestEvent } from '@octokit/webhooks-types'
+import { createContext } from './create-context'
+import { createSection } from './create-section'
+
+export function createSlackMessage(): void {
+  const payload = github.context.payload as PullRequestEvent
+
+  if (payload.action !== 'opened') {
+    throw new Error(
+      'This action is supposed to be run on pull_request opened event'
+    )
+  }
+
+  if (!payload.pull_request) {
+    throw new Error('This action is supposed to be run on pull_request event')
+  }
+
+  const section = createSection(payload)
+  const context = createContext(payload)
+
+  const message = JSON.stringify({ blocks: [section, context] })
+
+  console.log(message);
+
+  core.setOutput('message', message)
+}
diff --git a/src/main.ts b/src/main.ts
index c804f90..68a0331 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1,5 +1,5 @@
 import * as core from '@actions/core'
-import { wait } from './wait'
+import { createSlackMessage } from './create-slack-message'
 
 /**
  * The main function for the action.
@@ -7,18 +7,7 @@ import { wait } from './wait'
  */
 export async function run(): Promise<void> {
   try {
-    const ms: string = core.getInput('milliseconds')
-
-    // Debug logs are only output if the `ACTIONS_STEP_DEBUG` secret is true
-    core.debug(`Waiting ${ms} milliseconds ...`)
-
-    // Log the current timestamp, wait, then log the new timestamp
-    core.debug(new Date().toTimeString())
-    await wait(parseInt(ms, 10))
-    core.debug(new Date().toTimeString())
-
-    // Set outputs for other workflow steps to use
-    core.setOutput('time', new Date().toTimeString())
+    createSlackMessage()
   } catch (error) {
     // Fail the workflow run if an error occurs
     if (error instanceof Error) core.setFailed(error.message)
diff --git a/src/to-slack-user.ts b/src/to-slack-user.ts
new file mode 100644
index 0000000..75609e7
--- /dev/null
+++ b/src/to-slack-user.ts
@@ -0,0 +1,21 @@
+/**
+ * Converts a GitHub username to a Slack username mention.
+ * If no mapping exists, returns the original GitHub username.
+ *
+ * @param githubUsername - The GitHub username to map.
+ * @returns The Slack mention (e.g., `<@Ryohei>`) or the original GitHub username.
+ */
+export function toSlackUser(githubUsername: string): string {
+  const userMappings: Record<string, string> = {
+    rysiva: 'Ryohei',
+    resnoa: 'resident noah'
+  }
+
+  const slackUsername = userMappings[githubUsername]
+  if (!slackUsername) {
+    console.warn(`No mapping found for GitHub username: ${githubUsername}`)
+    return githubUsername
+  }
+
+  return `<@${slackUsername}>`
+}
diff --git a/src/to-slack-users.ts b/src/to-slack-users.ts
new file mode 100644
index 0000000..86d957a
--- /dev/null
+++ b/src/to-slack-users.ts
@@ -0,0 +1,11 @@
+import { User, Team } from '@octokit/webhooks-types'
+import { toSlackUser } from './to-slack-user'
+
+export function toSlackUsers(requestedReviewers: (User | Team)[]): string[] {
+  return requestedReviewers.map(reviewer => {
+    if ('login' in reviewer) {
+      return toSlackUser(reviewer.login)
+    }
+    throw new Error('ログインプロパティが見つかりません')
+  })
+}
diff --git a/src/wait.ts b/src/wait.ts
deleted file mode 100644
index 0ddf692..0000000
--- a/src/wait.ts
+++ /dev/null
@@ -1,14 +0,0 @@
-/**
- * Wait for a number of milliseconds.
- * @param milliseconds The number of milliseconds to wait.
- * @returns {Promise<string>} Resolves with 'done!' after the wait is over.
- */
-export async function wait(milliseconds: number): Promise<string> {
-  return new Promise(resolve => {
-    if (isNaN(milliseconds)) {
-      throw new Error('milliseconds not a number')
-    }
-
-    setTimeout(() => resolve('done!'), milliseconds)
-  })
-}