diff --git a/package.json b/package.json
index bb44951e8..3057c5d80 100644
--- a/package.json
+++ b/package.json
@@ -27,7 +27,7 @@
 		"check:connect": "cd packages/backend && pnpm check:connect",
 		"migrateandstart": "pnpm migrate && pnpm start",
 		"watch": "pnpm dev",
-		"dev": "pnpm -r dev",
+		"dev": "node scripts/dev.mjs",
 		"lint": "pnpm -r lint",
 		"cy:open": "pnpm cypress open --browser --e2e --config-file=cypress.config.ts",
 		"cy:run": "pnpm cypress run",
diff --git a/packages/backend/package.json b/packages/backend/package.json
index 17113a5e0..504cc882f 100644
--- a/packages/backend/package.json
+++ b/packages/backend/package.json
@@ -16,7 +16,8 @@
 		"watch:swc": "swc src -d built -D -w",
 		"build:tsc": "tsc -p tsconfig.json && tsc-alias -p tsconfig.json",
 		"watch": "node watch.mjs",
-		"dev": "node ./built/boot/entry.js",
+		"restart": "pnpm build && pnpm start",
+		"dev": "nodemon -w src -e ts,js,mjs,cjs,json --exec \"cross-env NODE_ENV=development pnpm run restart\"",
 		"typecheck": "tsc --noEmit",
 		"eslint": "eslint --quiet \"src/**/*.ts\"",
 		"lint": "pnpm typecheck && pnpm eslint",
@@ -226,6 +227,7 @@
 		"execa": "8.0.1",
 		"jest": "29.7.0",
 		"jest-mock": "29.7.0",
+		"nodemon": "3.0.2",
 		"simple-oauth2": "5.0.0"
 	}
 }
diff --git a/packages/frontend/@types/global.d.ts b/packages/frontend/@types/global.d.ts
index 390f63990..7d9335cc5 100644
--- a/packages/frontend/@types/global.d.ts
+++ b/packages/frontend/@types/global.d.ts
@@ -13,3 +13,6 @@ declare const _PERF_PREFIX_: string;
 declare const _DATA_TRANSFER_DRIVE_FILE_: string;
 declare const _DATA_TRANSFER_DRIVE_FOLDER_: string;
 declare const _DATA_TRANSFER_DECK_COLUMN_: string;
+
+// for dev-mode
+declare const _LANGS_FULL_: string[][];
diff --git a/packages/frontend/src/_dev_boot_.ts b/packages/frontend/src/_dev_boot_.ts
index 2e95a0357..d01a95704 100644
--- a/packages/frontend/src/_dev_boot_.ts
+++ b/packages/frontend/src/_dev_boot_.ts
@@ -8,4 +8,88 @@
 // (pnpm start時はpugファイルの中で静的リソースとして読み込むようになっており、この問題は起こっていない)
 import '@tabler/icons-webfont/tabler-icons.scss';
 
+await main();
+
 import('@/_boot_.js');
+
+/**
+ * backend/src/server/web/boot.jsで差し込まれている起動処理のうち、最低限必要なものを模倣するための処理
+ */
+async function main() {
+	const forceError = localStorage.getItem('forceError');
+	if (forceError != null) {
+		renderError('FORCED_ERROR', 'This error is forced by having forceError in local storage.');
+	}
+
+	//#region Detect language & fetch translations
+
+	// dev-modeの場合は常に取り直す
+	const supportedLangs = _LANGS_.map(it => it[0]);
+	let lang: string | null | undefined = localStorage.getItem('lang');
+	if (lang == null || !supportedLangs.includes(lang)) {
+		if (supportedLangs.includes(navigator.language)) {
+			lang = navigator.language;
+		} else {
+			lang = supportedLangs.find(x => x.split('-')[0] === navigator.language);
+
+			// Fallback
+			if (lang == null) lang = 'en-US';
+		}
+	}
+
+	// TODO:今のままだと言語ファイル変更後はpnpm devをリスタートする必要があるので、chokidarを使ったり等で対応できるようにする
+	const locale = _LANGS_FULL_.find(it => it[0] === lang);
+	localStorage.setItem('lang', lang);
+	localStorage.setItem('locale', JSON.stringify(locale[1]));
+	localStorage.setItem('localeVersion', _VERSION_);
+	//#endregion
+
+	//#region Theme
+	const theme = localStorage.getItem('theme');
+	if (theme) {
+		for (const [k, v] of Object.entries(JSON.parse(theme))) {
+			document.documentElement.style.setProperty(`--${k}`, v.toString());
+
+			// HTMLの theme-color 適用
+			if (k === 'htmlThemeColor') {
+				for (const tag of document.head.children) {
+					if (tag.tagName === 'META' && tag.getAttribute('name') === 'theme-color') {
+						tag.setAttribute('content', v);
+						break;
+					}
+				}
+			}
+		}
+	}
+	const colorScheme = localStorage.getItem('colorScheme');
+	if (colorScheme) {
+		document.documentElement.style.setProperty('color-scheme', colorScheme);
+	}
+	//#endregion
+
+	const fontSize = localStorage.getItem('fontSize');
+	if (fontSize) {
+		document.documentElement.classList.add('f-' + fontSize);
+	}
+
+	const useSystemFont = localStorage.getItem('useSystemFont');
+	if (useSystemFont) {
+		document.documentElement.classList.add('useSystemFont');
+	}
+
+	const wallpaper = localStorage.getItem('wallpaper');
+	if (wallpaper) {
+		document.documentElement.style.backgroundImage = `url(${wallpaper})`;
+	}
+
+	const customCss = localStorage.getItem('customCss');
+	if (customCss && customCss.length > 0) {
+		const style = document.createElement('style');
+		style.innerHTML = customCss;
+		document.head.appendChild(style);
+	}
+}
+
+function renderError(code: string, details?: string) {
+	console.log(code, details);
+}
diff --git a/packages/frontend/vite.config.local-dev.ts b/packages/frontend/vite.config.local-dev.ts
index 6b6394a72..aea46f423 100644
--- a/packages/frontend/vite.config.local-dev.ts
+++ b/packages/frontend/vite.config.local-dev.ts
@@ -1,5 +1,6 @@
 import dns from 'dns';
 import { defineConfig } from 'vite';
+import locales from '../../locales';
 import { getConfig } from './vite.config.js';
 
 dns.setDefaultResultOrder('ipv4first');
@@ -49,6 +50,11 @@ const devConfig = {
 			input: 'index.html',
 		},
 	},
+
+	define: {
+		...defaultConfig.define,
+		_LANGS_FULL_: JSON.stringify(Object.entries(locales)),
+	},
 };
 
 export default defineConfig(({ command, mode }) => devConfig);
diff --git a/packages/misskey-js/package.json b/packages/misskey-js/package.json
index 6a7712af9..0b54c6a59 100644
--- a/packages/misskey-js/package.json
+++ b/packages/misskey-js/package.json
@@ -6,6 +6,7 @@
 	"types": "./built/index.d.ts",
 	"scripts": {
 		"build": "tsc",
+		"watch": "nodemon -w src -e ts,js,cjs,mjs,json --exec \"pnpm run build\"",
 		"tsd": "tsd",
 		"api": "pnpm api-extractor run --local --verbose",
 		"api-prod": "pnpm api-extractor run --verbose",
@@ -32,9 +33,10 @@
 		"jest-fetch-mock": "3.0.3",
 		"jest-websocket-mock": "2.5.0",
 		"mock-socket": "9.3.1",
+		"ncp": "2.0.0",
+		"nodemon": "3.0.2",
 		"tsd": "0.29.0",
-		"typescript": "5.3.3",
-		"ncp": "2.0.0"
+		"typescript": "5.3.3"
 	},
 	"files": [
 		"built"
diff --git a/packages/sw/package.json b/packages/sw/package.json
index 039a6887a..990e99196 100644
--- a/packages/sw/package.json
+++ b/packages/sw/package.json
@@ -2,7 +2,7 @@
 	"name": "sw",
 	"private": true,
 	"scripts": {
-		"watch": "node build.js watch",
+		"watch": "nodemon -w ../../package.json -e json --exec \"node build.js watch\"",
 		"build": "node build.js",
 		"typecheck": "tsc --noEmit",
 		"eslint": "eslint --quiet src/**/*.ts",
@@ -18,6 +18,7 @@
 		"@typescript/lib-webworker": "npm:@types/serviceworker@0.0.67",
 		"eslint": "8.55.0",
 		"eslint-plugin-import": "2.29.0",
+		"nodemon": "3.0.2",
 		"typescript": "5.3.3"
 	},
 	"type": "module"
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 5afc58334..7c0bc470b 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -643,6 +643,9 @@ importers:
       jest-mock:
         specifier: 29.7.0
         version: 29.7.0
+      nodemon:
+        specifier: 3.0.2
+        version: 3.0.2
       simple-oauth2:
         specifier: 5.0.0
         version: 5.0.0
@@ -1041,6 +1044,9 @@ importers:
       ncp:
         specifier: 2.0.0
         version: 2.0.0
+      nodemon:
+        specifier: 3.0.2
+        version: 3.0.2
       tsd:
         specifier: 0.29.0
         version: 0.29.0
@@ -1105,6 +1111,9 @@ importers:
       eslint-plugin-import:
         specifier: 2.29.0
         version: 2.29.0(@typescript-eslint/parser@6.14.0)(eslint@8.55.0)
+      nodemon:
+        specifier: 3.0.2
+        version: 3.0.2
       typescript:
         specifier: 5.3.3
         version: 5.3.3
diff --git a/scripts/build-assets.mjs b/scripts/build-assets.mjs
index f8f09ec2f..2e1268130 100644
--- a/scripts/build-assets.mjs
+++ b/scripts/build-assets.mjs
@@ -95,6 +95,7 @@ if (process.argv.includes("--watch")) {
 	for await (const event of watcher) {
 		const filename = event.filename?.replaceAll('\\', '/');
 		if (/^[a-z]+-[A-Z]+\.yml/.test(filename)) {
+			console.log(`update ${filename} ...`)
 			locales = buildLocales();
 			await copyFrontendLocales()
 		}
diff --git a/scripts/build-pre.js b/scripts/build-pre.js
index bf3e355b5..ed75aa655 100644
--- a/scripts/build-pre.js
+++ b/scripts/build-pre.js
@@ -4,7 +4,24 @@
  */
 
 const fs = require('fs');
-const meta = require('../package.json');
+const packageJsonPath = __dirname + '/../package.json'
 
-fs.mkdirSync(__dirname + '/../built', { recursive: true });
-fs.writeFileSync(__dirname + '/../built/meta.json', JSON.stringify({ version: meta.version }), 'utf-8');
+function build() {
+	try {
+		const json = fs.readFileSync(packageJsonPath, 'utf-8')
+		const meta = JSON.parse(json);
+		fs.mkdirSync(__dirname + '/../built', { recursive: true });
+		fs.writeFileSync(__dirname + '/../built/meta.json', JSON.stringify({ version: meta.version }), 'utf-8');
+	} catch (e) {
+		console.error(e)
+	}
+}
+
+build();
+
+if (process.argv.includes("--watch")) {
+	fs.watch(packageJsonPath, (event, filename) => {
+		console.log(`update ${filename} ...`)
+		build()
+	})
+}
diff --git a/scripts/dev.mjs b/scripts/dev.mjs
index 1d06aa541..30dbebcf0 100644
--- a/scripts/dev.mjs
+++ b/scripts/dev.mjs
@@ -3,7 +3,6 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
-import fs from 'node:fs';
 import { dirname } from 'node:path';
 import { fileURLToPath } from 'node:url';
 import { execa } from 'execa';
@@ -11,8 +10,6 @@ import { execa } from 'execa';
 const _filename = fileURLToPath(import.meta.url);
 const _dirname = dirname(_filename);
 
-const vitePort = process.env.VITE_PORT ? ["--strictPort", "--port", process.env.VITE_PORT] : ["--strictPort"];
-
 await execa('pnpm', ['clean'], {
 	cwd: _dirname + '/../',
 	stdout: process.stdout,
@@ -31,19 +28,25 @@ await execa('pnpm', ['build-assets'], {
 	stderr: process.stderr,
 });
 
+execa('pnpm', ['build-pre', '--watch'], {
+	cwd: _dirname + '/../',
+	stdout: process.stdout,
+	stderr: process.stderr,
+});
+
 execa('pnpm', ['build-assets', '--watch'], {
 	cwd: _dirname + '/../',
 	stdout: process.stdout,
 	stderr: process.stderr,
 });
 
-execa('pnpm', ['--filter', 'backend', 'watch'], {
+execa('pnpm', ['--filter', 'backend', 'dev'], {
 	cwd: _dirname + '/../',
 	stdout: process.stdout,
 	stderr: process.stderr,
 });
 
-execa('pnpm', ['--filter', 'frontend', 'watch', ...vitePort], {
+execa('pnpm', ['--filter', 'frontend', 'dev'], {
 	cwd: _dirname + '/../',
 	stdout: process.stdout,
 	stderr: process.stderr,
@@ -55,27 +58,8 @@ execa('pnpm', ['--filter', 'sw', 'watch'], {
 	stderr: process.stderr,
 });
 
-const start = async () => {
-	try {
-		const stat = fs.statSync(_dirname + '/../packages/backend/built/boot/entry.js');
-		if (!stat) throw new Error('not exist yet');
-		if (stat.size === 0) throw new Error('not built yet');
-
-		const subprocess = await execa('pnpm', ['start'], {
-			cwd: _dirname + '/../',
-			stdout: process.stdout,
-			stderr: process.stderr,
-		});
-
-		// なぜかworkerだけが終了してmasterが残るのでその対策
-		process.on('SIGINT', () => {
-			subprocess.kill('SIGINT');
-			process.exit(0);
-		});
-	} catch (e) {
-		await new Promise(resolve => setTimeout(resolve, 3000));
-		start();
-	}
-};
-
-start();
+execa('pnpm', ['--filter', 'misskey-js', 'watch'], {
+	cwd: _dirname + '/../',
+	stdout: process.stdout,
+	stderr: process.stderr,
+});