diff --git a/app.js b/app.js
index c2a6f75..72fc432 100644
--- a/app.js
+++ b/app.js
@@ -1,34 +1,16 @@
-const { promisify } = require("util");
-const { App, ExpressReceiver } = require("@slack/bolt");
-const daraz = require("./");
+const { App: BoltApp } = require("@slack/bolt");
 
-class Receiver extends ExpressReceiver {
+class App extends BoltApp {
   /**
-   * @param {import("express").Request} req
-   * @param {import("express").Response} res
+   * @param  {import("@slack/bolt").AppOptions} opt
    */
-  requestHandler(req, res) {
-    // NOTE: See also https://api.slack.com/events-api#errors
-    res.header("x-slack-no-retry", "1");
-    if (req.headers["x-slack-retry-reason"] === "http_timeout")
-      return promisify(res.end)();
-
-    return super.requestHandler(req, res);
+  constructor(opt) {
+    super(opt);
+    const scripts = require("glob").sync("./scripts/*.js").map(require);
+    scripts.forEach((script) => {
+      if (Array.isArray(script)) return this.message(...script);
+      if (script instanceof Function) return script(this);
+    });
   }
 }
-
-const receiver = new Receiver({
-  signingSecret: process.env.SLACK_SIGNING_SECRET,
-});
-
-const app = daraz(
-  new App({
-    token: process.env.SLACK_BOT_TOKEN,
-    receiver,
-  })
-);
-
-(async () => {
-  await app.start(process.env.PORT || 8080);
-  console.log("Daraz-san ⚡ running");
-})();
+module.exports = App;
diff --git a/index.js b/index.js
deleted file mode 100644
index 5efe3e9..0000000
--- a/index.js
+++ /dev/null
@@ -1,9 +0,0 @@
-const scripts = require("glob").sync("./scripts/*.js").map(require);
-
-module.exports = (app) => {
-  scripts.forEach((script) => {
-    if (Array.isArray(script)) return app.message(...script);
-    if (script instanceof Function) return script(app);
-  });
-  return app;
-};
diff --git a/main.js b/main.js
new file mode 100644
index 0000000..6b52068
--- /dev/null
+++ b/main.js
@@ -0,0 +1,18 @@
+const App = require("./app");
+const Receiver = require("./receiver");
+
+async function main() {
+  const receiver = new Receiver({
+    signingSecret: process.env.SLACK_SIGNING_SECRET,
+  });
+
+  const app = new App({
+    token: process.env.SLACK_BOT_TOKEN,
+    receiver,
+  });
+
+  await app.start(process.env.PORT || 8080);
+  console.log("Daraz-san ⚡ running");
+}
+
+if (require.main === module) main();
diff --git a/package.json b/package.json
index df2376e..bf1359d 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,6 @@
   "name": "daraz-san",
   "version": "1.0.0",
   "description": "Daraz-san ⚡",
-  "main": "index.js",
   "author": "Kohei Watanabe <kou029w@gmail.com>",
   "contributors": [
     "SAKAGUCHI Takashi <takashi.sakaguchi@ummm.info>",
@@ -12,7 +11,7 @@
   "license": "MIT",
   "private": true,
   "scripts": {
-    "start": "node app.js"
+    "start": "node main.js"
   },
   "dependencies": {
     "@slack/bolt": "2.x",
diff --git a/receiver.js b/receiver.js
new file mode 100644
index 0000000..66eb0d3
--- /dev/null
+++ b/receiver.js
@@ -0,0 +1,18 @@
+const { promisify } = require("util");
+const { ExpressReceiver } = require("@slack/bolt");
+
+class Receiver extends ExpressReceiver {
+  /**
+   * @param {import("express").Request} req
+   * @param {import("express").Response} res
+   */
+  requestHandler(req, res) {
+    // NOTE: See also https://api.slack.com/events-api#errors
+    res.header("x-slack-no-retry", "1");
+    if (req.headers["x-slack-retry-reason"] === "http_timeout")
+      return promisify(res.end)();
+
+    return super.requestHandler(req, res);
+  }
+}
+module.exports = Receiver;