diff --git a/package.json b/package.json
index 776530559a..0c790899eb 100644
--- a/package.json
+++ b/package.json
@@ -130,7 +130,6 @@
 		"css-loader": "5.0.1",
 		"cssnano": "4.1.10",
 		"dateformat": "4.3.1",
-		"deep-entries": "3.1.0",
 		"diskusage": "1.1.3",
 		"double-ended-queue": "2.1.0-0",
 		"escape-regexp": "0.0.1",
diff --git a/src/client/i18n.ts b/src/client/i18n.ts
index aeecb58a3e..fbc10a0bad 100644
--- a/src/client/i18n.ts
+++ b/src/client/i18n.ts
@@ -1,49 +1,6 @@
 import { markRaw } from 'vue';
 import { locale } from '@/config';
-
-export class I18n<T extends Record<string, any>> {
-	public locale: T;
-
-	constructor(locale: T) {
-		this.locale = locale;
-
-		if (_DEV_) {
-			console.log('i18n', this.locale);
-		}
-
-		//#region BIND
-		this.t = this.t.bind(this);
-		//#endregion
-	}
-
-	// string にしているのは、ドット区切りでのパス指定を許可するため
-	// なるべくこのメソッド使うよりもlocale直接参照の方がvueのキャッシュ効いてパフォーマンスが良いかも
-	public t(key: string, args?: Record<string, any>): string {
-		try {
-			let str = key.split('.').reduce((o, i) => o[i], this.locale) as string;
-
-			if (_DEV_) {
-				if (!str.includes('{')) {
-					console.warn(`i18n: '${key}' has no any arg. so ref prop directly instead of call this method.`);
-				}
-			}
-
-			if (args) {
-				for (const [k, v] of Object.entries(args)) {
-					str = str.replace(`{${k}}`, v);
-				}
-			}
-			return str;
-		} catch (e) {
-			if (_DEV_) {
-				console.warn(`missing localization '${key}'`);
-				return `⚠'${key}'⚠`;
-			}
-
-			return key;
-		}
-	}
-}
+import { I18n } from '@/scripts/i18n';
 
 export const i18n = markRaw(new I18n(locale));
 
diff --git a/src/client/init.ts b/src/client/init.ts
index f329d22251..8fcabea119 100644
--- a/src/client/init.ts
+++ b/src/client/init.ts
@@ -38,18 +38,18 @@ if (localStorage.getItem('vuex') != null) {
 
 import * as Sentry from '@sentry/browser';
 import { Integrations } from '@sentry/tracing';
-import { createApp, watch } from 'vue';
+import { createApp, toRaw, watch } from 'vue';
 import { FontAwesomeIcon } from '@fortawesome/vue-fontawesome';
 
 import widgets from '@/widgets';
 import directives from '@/directives';
 import components from '@/components';
-import { version, ui, lang, host } from '@/config';
+import { version, ui, lang, host, locale } from '@/config';
 import { router } from '@/router';
 import { applyTheme } from '@/scripts/theme';
 import { isDeviceDarkmode } from '@/scripts/is-device-darkmode';
 import { i18n } from '@/i18n';
-import { stream, isMobile, dialog, post } from '@/os';
+import { api, stream, isMobile, dialog, post } from '@/os';
 import * as sound from '@/scripts/sound';
 import { $i, refreshAccount, login, updateAccount, signout } from '@/account';
 import { defaultStore, ColdDeviceStorage } from '@/store';
@@ -171,7 +171,48 @@ fetchInstance().then(() => {
 	localStorage.setItem('v', instance.version);
 
 	// Init service worker
-	//if (this.store.state.instance.meta.swPublickey) this.registerSw(this.store.state.instance.meta.swPublickey);
+	if (instance.swPublickey &&
+		('serviceWorker' in navigator) &&
+		('PushManager' in window) && $i && $i.token
+		) {
+		navigator.serviceWorker.ready.then(registration => {
+			registration.active?.postMessage({
+				msg: 'initialize',
+				locale,
+				i: toRaw($i),
+			});
+			// SEE: https://developer.mozilla.org/en-US/docs/Web/API/PushManager/subscribe#Parameters
+			registration.pushManager.subscribe({
+				userVisibleOnly: true,
+				applicationServerKey: urlBase64ToUint8Array(instance.swPublickey)
+			}).then(subscription => {
+				function encode(buffer: ArrayBuffer | null) {
+					return btoa(String.fromCharCode.apply(null, new Uint8Array(buffer)));
+				}
+
+				// Register
+				api('sw/register', {
+					endpoint: subscription.endpoint,
+					auth: encode(subscription.getKey('auth')),
+					publickey: encode(subscription.getKey('p256dh'))
+				});
+			})
+			// When subscribe failed
+			.catch(async (err: Error) => {
+				// 通知が許可されていなかったとき
+				if (err.name === 'NotAllowedError') {
+					return;
+				}
+
+				// 違うapplicationServerKey (または gcm_sender_id)のサブスクリプションが
+				// 既に存在していることが原因でエラーになった可能性があるので、
+				// そのサブスクリプションを解除しておく
+				const subscription = await registration.pushManager.getSubscription();
+				if (subscription) subscription.unsubscribe();
+			});
+		});
+
+	};
 });
 
 stream.init($i);
@@ -354,3 +395,22 @@ if ($i) {
 		signout();
 	});
 }
+
+/**
+ * Convert the URL safe base64 string to a Uint8Array
+ * @param base64String base64 string
+ */
+function urlBase64ToUint8Array(base64String: string): Uint8Array {
+	const padding = '='.repeat((4 - base64String.length % 4) % 4);
+	const base64 = (base64String + padding)
+		.replace(/-/g, '+')
+		.replace(/_/g, '/');
+
+	const rawData = window.atob(base64);
+	const outputArray = new Uint8Array(rawData.length);
+
+	for (let i = 0; i < rawData.length; ++i) {
+		outputArray[i] = rawData.charCodeAt(i);
+	}
+	return outputArray;
+}
diff --git a/src/client/scripts/i18n.ts b/src/client/scripts/i18n.ts
new file mode 100644
index 0000000000..d535e236bb
--- /dev/null
+++ b/src/client/scripts/i18n.ts
@@ -0,0 +1,44 @@
+// Notice: Service Workerでも使用します
+export class I18n<T extends Record<string, any>> {
+	public locale: T;
+
+	constructor(locale: T) {
+		this.locale = locale;
+
+		if (_DEV_) {
+			console.log('i18n', this.locale);
+		}
+
+		//#region BIND
+		this.t = this.t.bind(this);
+		//#endregion
+	}
+
+	// string にしているのは、ドット区切りでのパス指定を許可するため
+	// なるべくこのメソッド使うよりもlocale直接参照の方がvueのキャッシュ効いてパフォーマンスが良いかも
+	public t(key: string, args?: Record<string, any>): string {
+		try {
+			let str = key.split('.').reduce((o, i) => o[i], this.locale) as string;
+
+			if (_DEV_) {
+				if (!str.includes('{')) {
+					console.warn(`i18n: '${key}' has no any arg. so ref prop directly instead of call this method.`);
+				}
+			}
+
+			if (args) {
+				for (const [k, v] of Object.entries(args)) {
+					str = str.replace(`{${k}}`, v);
+				}
+			}
+			return str;
+		} catch (e) {
+			if (_DEV_) {
+				console.warn(`missing localization '${key}'`);
+				return `⚠'${key}'⚠`;
+			}
+
+			return key;
+		}
+	}
+}
diff --git a/src/client/sw/compose-notification.ts b/src/client/sw/compose-notification.ts
index 17421db5c8..101cb3bcdb 100644
--- a/src/client/sw/compose-notification.ts
+++ b/src/client/sw/compose-notification.ts
@@ -1,8 +1,12 @@
 import { getNoteSummary } from '../../misc/get-note-summary';
 import getUserName from '../../misc/get-user-name';
-import { i18n } from '@/sw/i18n';
 
-export default async function(type, data): Promise<[string, NotificationOptions]> {
+export default async function(type, data, i18n): Promise<[string, NotificationOptions] | null> {
+	if (!i18n) {
+		console.log('no i18n')
+		return null
+	};
+
 	switch (type) {
 		case 'driveFileCreated': // TODO (Server Side)
 			return [i18n.t('_notification.fileUploaded'), {
diff --git a/src/client/sw/i18n.ts b/src/client/sw/i18n.ts
deleted file mode 100644
index 9b3e3b2f4d..0000000000
--- a/src/client/sw/i18n.ts
+++ /dev/null
@@ -1,5 +0,0 @@
-import { I18n } from '@/i18n';
-
-export const i18n = new I18n({
-	// TODO
-});
diff --git a/src/client/sw/sw.ts b/src/client/sw/sw.ts
index 91d668c27b..f429a37eb3 100644
--- a/src/client/sw/sw.ts
+++ b/src/client/sw/sw.ts
@@ -4,6 +4,11 @@
 declare var self: ServiceWorkerGlobalScope;
 
 import composeNotification from '@/sw/compose-notification';
+import { I18n } from '@/scripts/i18n';
+
+export let i18n: I18n<any>;
+
+let i: string;
 
 const version = _VERSION_;
 const cacheName = `mk-cache-${version}`;
@@ -12,8 +17,6 @@ const apiUrl = `${location.origin}/api/`;
 
 // インストールされたとき
 self.addEventListener('install', ev => {
-	console.info('installed');
-
 	ev.waitUntil(
 		caches.open(cacheName)
 			.then(cache => {
@@ -59,8 +62,31 @@ self.addEventListener('push', ev => {
 		// クライアントがあったらストリームに接続しているということなので通知しない
 		if (clients.length != 0) return;
 
-		const { type, body } = ev.data.json();
+		const { type, body } = ev.data?.json();
 
-		return self.registration.showNotification(...(await composeNotification(type, body)));
+		const n = await composeNotification(type, body, i18n);
+		if (n) return self.registration.showNotification(...n);
 	}));
 });
+
+// クライアントのpostMessageを処理します
+self.addEventListener('message', ev => {
+	switch(ev.data) {
+		case 'clear':
+			return; // TODO
+		default:
+			break;
+	}
+
+	if (typeof ev.data === 'object') {
+		const otype = Object.prototype.toString.call(ev.data).slice(8, -1).toLowerCase();
+
+		if (otype === 'object') {
+			if (ev.data.msg === 'initialize') {
+				console.log('initialize')
+				i = ev.data.$i;
+				i18n = new I18n(ev.data.locale);
+			}
+		}
+	}
+});
diff --git a/src/server/web/boot.js b/src/server/web/boot.js
index eb7c21fb63..3c2d83fe83 100644
--- a/src/server/web/boot.js
+++ b/src/server/web/boot.js
@@ -33,9 +33,8 @@
 		}
 
 		const res = await fetch(`/assets/locales/${lang}.${v}.json`);
-		const json = await res.json();
 		localStorage.setItem('lang', lang);
-		localStorage.setItem('locale', JSON.stringify(json));
+		localStorage.setItem('locale', await res.text());
 	}
 	//#endregion
 
@@ -73,6 +72,10 @@
 	head.appendChild(script);
 	//#endregion
 
+	//#region Service Worker
+	navigator.serviceWorker.register(`/sw.${v}.js`)
+	//#endregion
+
 	//#region Theme
 	const theme = localStorage.getItem('theme');
 	if (theme) {
diff --git a/yarn.lock b/yarn.lock
index c34ee573a6..bd73c4e2ec 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3258,11 +3258,6 @@ decompress-response@^6.0.0:
   dependencies:
     mimic-response "^3.1.0"
 
-deep-entries@3.1.0:
-  version "3.1.0"
-  resolved "https://registry.yarnpkg.com/deep-entries/-/deep-entries-3.1.0.tgz#e456aa791d01b045641c75e41e170c0c95a9d472"
-  integrity sha512-pCpcCqx/hclnT2e4mMlM9geG8XIaxWN+yNKJHHwu1FZyYKErKU/fPztYYSk2HwnqRPf55cDEXraV6MLv8I5FrA==
-
 deep-eql@^3.0.1:
   version "3.0.1"
   resolved "https://registry.yarnpkg.com/deep-eql/-/deep-eql-3.0.1.tgz#dfc9404400ad1c8fe023e7da1df1c147c4b444df"