diff --git a/aws/serverless.yml b/aws/serverless.yml
index 2dfd48cd..94da56aa 100644
--- a/aws/serverless.yml
+++ b/aws/serverless.yml
@@ -116,11 +116,6 @@ functions:
     events:
       - schedule:
           rate: 'cron(5 * * * ? *)'
-  watch-inshi:
-    handler: src/watch-inshi/index.handler
-    events:
-      - schedule:
-          rate: 'cron(10 * * * ? *)'
   sandbox-logger:
     handler: src/slack/sandbox/logger/index.handler
     events:
diff --git a/aws/src/watch-inshi/index.ts b/aws/src/watch-inshi/index.ts
deleted file mode 100644
index c3f86243..00000000
--- a/aws/src/watch-inshi/index.ts
+++ /dev/null
@@ -1,160 +0,0 @@
-import type { ScheduledHandler } from 'aws-lambda';
-import { axios } from '@/lib/axios';
-import 'source-map-support/register';
-import { envvar } from '@/lib/envvar';
-import { slack } from '@/lib/slack/client';
-import cheerio from 'cheerio';
-import * as diff from 'diff';
-import { getBucketName, s3 } from '@/lib/s3';
-import type { MessageAttachment } from '@slack/web-api';
-import { source } from 'common-tags';
-import type { Option } from 'ts-results';
-import { None, Some } from 'ts-results';
-import { S3ServiceException, NoSuchKey } from '@aws-sdk/client-s3';
-import { Size, validateSize } from '@/lib/validate';
-import assert from 'assert';
-import { getColor } from '@/lib/color';
-
-const watchingUrl = 'https://www.i.u-tokyo.ac.jp/edu/entra/index.shtml';
-
-const fetchHTML = async (): Promise<string> =>
-  (await axios.get(watchingUrl)).data as string;
-
-/**
- * HTMLをパースしてテキストに変換
- */
-const extractTextFromHTML = (html: string): string => {
-  const $ = cheerio.load(html);
-  return $('#free').text();
-};
-
-/**
- * 差分を計算
- */
-export const calcDiff = (oldText: string, newText: string): Option<diff.Change[]> => {
-  const changes = diff.diffLines(oldText, newText, { ignoreWhitespace: true });
-  if (changes.length === 1) {
-    return None;
-  }
-  return Some(changes);
-};
-
-/**
- * 差分をSlack用に整形
- */
-const formatDiff = (changes: diff.Change[]): MessageAttachment[] =>
-  // TODO: もっといい感じに
-  changes
-    .filter(change => change.added || change.removed)
-    .filter(change => change.value.trim())
-    .map(change => (change.added ? {
-      color: getColor('add', { hashed: true }),
-      title: '追加',
-      text: change.value,
-    } : {
-      color: getColor('delete', { hashed: true }),
-      title: '削除',
-      text: change.value,
-    }));
-
-/**
- * 前回取得したHTMLを取得する
- */
-const loadOldText = async (): Promise<Option<string>> => {
-  try {
-    const res = await s3.getObject({
-      /* eslint-disable @typescript-eslint/naming-convention */
-      Bucket: getBucketName('default'),
-      Key: 'watch-inshi/ist/index.txt',
-      /* eslint-enable @typescript-eslint/naming-convention */
-    });
-    assert(res.Body !== undefined);
-    return Some(await res.Body.transformToString());
-  } catch (error) {
-    if (error instanceof NoSuchKey) {
-      return None;
-    }
-    if (error instanceof S3ServiceException && error.name === 'AccessDenied') {
-      return None;
-    }
-    throw error;
-  }
-};
-
-/**
- * 今回取得したHTMLを保存する
- */
-const saveNewText = async (text: string): Promise<void> => {
-  const buf = Buffer.from(text);
-
-  if (!validateSize(buf, new Size(1, 'mb'))) {
-    throw new Error(`Buffer is too big: ${buf.length} bytes`);
-  }
-
-  await s3.putObject({
-    /* eslint-disable @typescript-eslint/naming-convention */
-    Bucket: getBucketName('default'),
-    Key: 'watch-inshi/ist/index.txt',
-    Body: buf,
-    /* eslint-enable @typescript-eslint/naming-convention */
-  });
-};
-
-/**
- * お知らせを Slack に通知する
- */
-const notify = async (attachments: MessageAttachment[]) => {
-  await (await slack.bot).chat.postMessage({
-    /* eslint-disable @typescript-eslint/naming-convention */
-    channel: await envvar.get('slack/channel/inshi-ist'),
-    username: '院試に詳しい芹沢あさひ',
-    icon_emoji: ':serizawa-asahi:',
-    text: source`
-      冬優子ちゃん大変っす！院試情報が更新されたっすよ！
-      ${watchingUrl}
-    `,
-    attachments,
-    /* eslint-enable @typescript-eslint/naming-convention */
-  });
-};
-
-/**
- * Lambda が呼ばれたときにする本質的な処理
- */
-export const main = async (): Promise<void> => {
-  const oldText = await loadOldText();
-
-  // 現在のお知らせ一覧ページを取得
-  const newHTML = await fetchHTML();
-  const newText = extractTextFromHTML(newHTML);
-  // 取得した HTML を保存
-  await saveNewText(newText);
-
-  if (!oldText.some) { // TODO: somehow option.none does not work as type guard
-    console.log('No saved HTML found. Skipping notification.');
-    return;
-  }
-
-  // 差分を計算
-  const changes = calcDiff(oldText.val, newText);
-  if (!changes.some) {
-    console.log('No changes. Skipping notification.');
-    return;
-  }
-  // Slack 投稿用に差分を整形
-  const attachments = formatDiff(changes.val);
-  // 新規お知らせを Slack に通知
-  await notify(attachments);
-};
-
-/**
- * Lambda で実行されるエントリーポイント
- *
- * Lambda specific な部分はこの部分で処理し，
- * 本質的な処理は main に書く。
- * 定期実行系は大抵非本質処理がいらないので，
- * 今回は main を呼ぶだけ。
- */
-export const handler: ScheduledHandler = async () => {
-  await main();
-};