diff --git a/guide/app/layout.tsx b/guide/app/layout.tsx
index 60195ab8..f36b9205 100644
--- a/guide/app/layout.tsx
+++ b/guide/app/layout.tsx
@@ -6,76 +6,142 @@ import {
 	usePageLoaderData,
 	MainNavigation,
 } from '~/components';
-import { logo } from '~/util';
+import { allLanguages, getLanguage, logo } from '~/util';
 
-const menus: Menu[] = [
-	{
-		title: 'Getting Started',
-		links: [
-			{ title: 'Overview', to: '/' },
-			{ title: 'Tutorial', to: '/tutorial' },
-			{ title: 'Upgrading to v1', to: '/upgrading-v1' },
-			{ title: 'GitHub', to: 'https://github.com/edmundhung/conform' },
-		],
-	},
-	{
-		title: 'Guides',
-		links: [
-			{ title: 'Validation', to: '/validation' },
-			{ title: 'Nested object and Array', to: '/complex-structures' },
-			{ title: 'Intent button', to: '/intent-button' },
-			{ title: 'Accessibility', to: '/accessibility' },
-			{ title: 'Checkbox and Radio Group', to: '/checkbox-and-radio-group' },
-			{ title: 'File Upload', to: '/file-upload' },
-		],
-	},
-	{
-		title: 'Integration',
-		links: [
-			{ title: 'UI Libraries', to: '/integration/ui-libraries' },
-			{ title: 'Remix', to: '/integration/remix' },
-			{ title: 'Next.js', to: '/integration/nextjs' },
-		],
-	},
-	{
-		title: 'API Reference',
-		links: [
-			{ title: 'useForm', to: '/api/react/useForm' },
-			{ title: 'useField', to: '/api/react/useField' },
-			{ title: 'useFormMetadata', to: '/api/react/useFormMetadata' },
-			{ title: 'useInputControl', to: '/api/react/useInputControl' },
-			{ title: 'FormProvider', to: '/api/react/FormProvider' },
-			{ title: 'FormStateInput', to: '/api/react/FormStateInput' },
-		],
-	},
-	{
-		title: 'Utilities',
-		links: [
-			{ title: 'getFormProps', to: '/api/react/getFormProps' },
-			{ title: 'getFieldsetProps', to: '/api/react/getFieldsetProps' },
-			{ title: 'getInputProps', to: '/api/react/getInputProps' },
-			{ title: 'getSelectProps', to: '/api/react/getSelectProps' },
-			{ title: 'getTextareaProps', to: '/api/react/getTextareaProps' },
-			{ title: 'getCollectionProps', to: '/api/react/getCollectionProps' },
-		],
-	},
-	{
-		title: 'Schema related',
-		links: [
-			{ title: 'parseWithZod', to: '/api/zod/parseWithZod' },
-			{ title: 'parseWithYup', to: '/api/yup/parseWithYup' },
-			{ title: 'getZodConstraint', to: '/api/zod/getZodConstraint' },
-			{ title: 'getYupConstraint', to: '/api/yup/getYupConstraint' },
-		],
-	},
-];
+const menus: { [code: string]: Menu[] } = {
+	en: [
+		{
+			title: 'Getting Started',
+			links: [
+				{ title: 'Overview', to: '/' },
+				{ title: 'Tutorial', to: '/tutorial' },
+				{ title: 'Upgrading to v1', to: '/upgrading-v1' },
+				{ title: 'GitHub', to: 'https://github.com/edmundhung/conform' },
+			],
+		},
+		{
+			title: 'Guides',
+			links: [
+				{ title: 'Validation', to: '/validation' },
+				{ title: 'Nested object and Array', to: '/complex-structures' },
+				{ title: 'Intent button', to: '/intent-button' },
+				{ title: 'Accessibility', to: '/accessibility' },
+				{ title: 'Checkbox and Radio Group', to: '/checkbox-and-radio-group' },
+				{ title: 'File Upload', to: '/file-upload' },
+			],
+		},
+		{
+			title: 'Integration',
+			links: [
+				{ title: 'UI Libraries', to: '/integration/ui-libraries' },
+				{ title: 'Remix', to: '/integration/remix' },
+				{ title: 'Next.js', to: '/integration/nextjs' },
+			],
+		},
+		{
+			title: 'API Reference',
+			links: [
+				{ title: 'useForm', to: '/api/react/useForm' },
+				{ title: 'useField', to: '/api/react/useField' },
+				{ title: 'useFormMetadata', to: '/api/react/useFormMetadata' },
+				{ title: 'useInputControl', to: '/api/react/useInputControl' },
+				{ title: 'FormProvider', to: '/api/react/FormProvider' },
+				{ title: 'FormStateInput', to: '/api/react/FormStateInput' },
+			],
+		},
+		{
+			title: 'Utilities',
+			links: [
+				{ title: 'getFormProps', to: '/api/react/getFormProps' },
+				{ title: 'getFieldsetProps', to: '/api/react/getFieldsetProps' },
+				{ title: 'getInputProps', to: '/api/react/getInputProps' },
+				{ title: 'getSelectProps', to: '/api/react/getSelectProps' },
+				{ title: 'getTextareaProps', to: '/api/react/getTextareaProps' },
+				{ title: 'getCollectionProps', to: '/api/react/getCollectionProps' },
+			],
+		},
+		{
+			title: 'Schema related',
+			links: [
+				{ title: 'parseWithZod', to: '/api/zod/parseWithZod' },
+				{ title: 'parseWithYup', to: '/api/yup/parseWithYup' },
+				{ title: 'getZodConstraint', to: '/api/zod/getZodConstraint' },
+				{ title: 'getYupConstraint', to: '/api/yup/getYupConstraint' },
+			],
+		},
+	],
+	ja: [
+		{
+			title: 'はじめに',
+			links: [
+				{ title: '概要', to: '/' },
+				{ title: 'チュートリアル', to: '/tutorial' },
+				{ title: 'v1 へのアップグレード', to: '/upgrading-v1' },
+				{ title: 'GitHub', to: 'https://github.com/edmundhung/conform' },
+			],
+		},
+		{
+			title: 'ガイド',
+			links: [
+				{ title: 'バリデーション', to: '/validation' },
+				{ title: 'ネストされたオブジェクトと配列', to: '/complex-structures' },
+				{ title: 'インテントボタン', to: '/intent-button' },
+				{ title: 'アクセシビリティ', to: '/accessibility' },
+				{
+					title: 'チェックボックスとラジオグループ',
+					to: '/checkbox-and-radio-group',
+				},
+				{ title: 'ファイルのアップロード', to: '/file-upload' },
+			],
+		},
+		{
+			title: 'インテグレーション',
+			links: [
+				{ title: 'UI ライブラリ', to: '/integration/ui-libraries' },
+				{ title: 'Remix', to: '/integration/remix' },
+				{ title: 'Next.js', to: '/integration/nextjs' },
+			],
+		},
+		{
+			title: 'API リファレンス',
+			links: [
+				{ title: 'useForm', to: '/api/react/useForm' },
+				{ title: 'useField', to: '/api/react/useField' },
+				{ title: 'useFormMetadata', to: '/api/react/useFormMetadata' },
+				{ title: 'useInputControl', to: '/api/react/useInputControl' },
+				{ title: 'FormProvider', to: '/api/react/FormProvider' },
+				{ title: 'FormStateInput', to: '/api/react/FormStateInput' },
+			],
+		},
+		{
+			title: 'ユーティリティ',
+			links: [
+				{ title: 'getFormProps', to: '/api/react/getFormProps' },
+				{ title: 'getFieldsetProps', to: '/api/react/getFieldsetProps' },
+				{ title: 'getInputProps', to: '/api/react/getInputProps' },
+				{ title: 'getSelectProps', to: '/api/react/getSelectProps' },
+				{ title: 'getTextareaProps', to: '/api/react/getTextareaProps' },
+				{ title: 'getCollectionProps', to: '/api/react/getCollectionProps' },
+			],
+		},
+		{
+			title: 'スキーマ関連',
+			links: [
+				{ title: 'parseWithZod', to: '/api/zod/parseWithZod' },
+				{ title: 'parseWithYup', to: '/api/yup/parseWithYup' },
+				{ title: 'getZodConstraint', to: '/api/zod/getZodConstraint' },
+				{ title: 'getYupConstraint', to: '/api/yup/getYupConstraint' },
+			],
+		},
+	],
+};
 
 export function Guide({
 	children,
 }: {
 	children: React.ReactNode;
 }): React.ReactNode {
-	const { owner, repo, ref } = useRootLoaderData();
+	const { owner, repo, ref, language } = useRootLoaderData();
 	const { file, toc } = usePageLoaderData() ?? {};
 	const location = useLocation();
 
@@ -106,16 +172,30 @@ export function Guide({
 	return (
 		<div className="xl:container mx-auto xl:grid xl:grid-cols-5 gap-10 px-8 relative">
 			<header className="bg-zinc-900 xl:bg-transparent sticky top-0 max-h-screen z-10 flex flex-col">
-				<div className="py-2 xl:py-4">
+				<div className="py-6 xl:py-10 flex items-end justify-between">
 					<Link
-						className="font-mono inline-block py-4 text-[.25rem] leading-[.25rem] xl:text-[.35rem] xl:leading-[.40rem] whitespace-pre"
+						className="font-mono inline-block text-[.20rem] leading-[.25rem] 2xl:text-[.3rem] 2xl:leading-[.3rem] whitespace-pre"
 						title="Conform"
 						to="/"
 					>
 						{logo}
 					</Link>
+					<select
+						className="bg-zinc-900 text-xs rounded-md py-1 pl-1 pr-8"
+						defaultValue={language.code}
+						onChange={(e) => {
+							const selectedLanguage = getLanguage(e.currentTarget.value);
+							window.location.href = `//${selectedLanguage.domain}${location.pathname}${location.search}`;
+						}}
+					>
+						{allLanguages.map(({ code, label }) => (
+							<option key={code} value={code}>
+								{label}
+							</option>
+						))}
+					</select>
 				</div>
-				<MainNavigation menus={menus} />
+				<MainNavigation menus={menus[language.code]} />
 			</header>
 			<main className="xl:col-span-3">{children}</main>
 			<footer className="xl:col-span-1 top-0 sticky py-4 xl:flex xl:flex-col xl:h-screen -mx-8 px-8 mt-8 xl:mt-0 border-t xl:border-t-0 border-dotted">
diff --git a/guide/app/routes/$.tsx b/guide/app/routes/$.tsx
index 7436f050..4fc5a9e0 100644
--- a/guide/app/routes/$.tsx
+++ b/guide/app/routes/$.tsx
@@ -7,7 +7,7 @@ import {
 import { useLoaderData } from '@remix-run/react';
 import { collectHeadings, parse } from '~/markdoc';
 import { Markdown } from '~/components';
-import { formatTitle, getFileContent } from '~/util';
+import { getDocPath, formatTitle, getFileContent } from '~/util';
 
 export const headers: HeadersFunction = ({ loaderHeaders }) => {
 	return loaderHeaders;
@@ -22,7 +22,7 @@ export const meta: MetaFunction<typeof loader> = ({ data }) => {
 };
 
 export async function loader({ params, context }: LoaderFunctionArgs) {
-	const file = `docs/${params['*']}.md`;
+	const file = `${getDocPath(context)}/${params['*']}.md`;
 	const readme = await getFileContent(context, file);
 	const content = parse(readme);
 
diff --git a/guide/app/routes/_index.tsx b/guide/app/routes/_index.tsx
index f124e525..17362710 100644
--- a/guide/app/routes/_index.tsx
+++ b/guide/app/routes/_index.tsx
@@ -7,7 +7,7 @@ import {
 import { useLoaderData } from '@remix-run/react';
 import { collectHeadings, parse } from '~/markdoc';
 import { Markdown } from '~/components';
-import { formatTitle, getFileContent } from '~/util';
+import { getDocPath, formatTitle, getFileContent } from '~/util';
 
 export const headers: HeadersFunction = ({ loaderHeaders }) => {
 	return loaderHeaders;
@@ -22,7 +22,7 @@ export const meta: MetaFunction<typeof loader> = ({ data }) => {
 };
 
 export async function loader({ context }: LoaderFunctionArgs) {
-	const file = 'docs/overview.md';
+	const file = `${getDocPath(context)}/overview.md`;
 	const readme = await getFileContent(context, file);
 	const content = parse(readme);
 
diff --git a/guide/app/util.ts b/guide/app/util.ts
index a724a478..1cbc19fe 100644
--- a/guide/app/util.ts
+++ b/guide/app/util.ts
@@ -1,6 +1,33 @@
 import type { Endpoints } from '@octokit/types';
 import type { AppLoadContext } from '@remix-run/cloudflare';
 
+interface Language {
+	code: string;
+	label: string;
+	branch: string;
+	docPath: string;
+	domain: string;
+	isDecodeUtf8: boolean;
+}
+export const allLanguages: Language[] = [
+	{
+		code: 'en',
+		label: 'en',
+		branch: 'main',
+		docPath: 'docs',
+		domain: 'conform.guide',
+		isDecodeUtf8: false,
+	},
+	{
+		code: 'ja',
+		label: 'ja',
+		branch: 'ja',
+		docPath: 'docs/ja',
+		domain: 'ja.conform.guide',
+		isDecodeUtf8: true,
+	},
+];
+
 export function invariant(
 	expectedCondition: boolean,
 	message: string,
@@ -11,10 +38,12 @@ export function invariant(
 }
 
 export function getMetadata(context: AppLoadContext) {
+	const branch = getBranch(context);
 	return {
 		owner: 'edmundhung',
 		repo: 'conform',
-		ref: getBranch(context),
+		ref: branch,
+		language: getLanguage(branch),
 	};
 }
 
@@ -34,11 +63,30 @@ export function getCache(context: AppLoadContext): KVNamespace {
 	return context.env.CACHE;
 }
 
+export const getDocPath = (context: AppLoadContext) => {
+	const { docPath } = getMetadata(context).language;
+	return docPath;
+};
+
+export function getLanguage(code: string): Language {
+	const language = allLanguages.find((lang) => lang.code === code);
+	return language ?? allLanguages[0]; // default to English
+}
+
+function base64DecodeUtf8(base64String: string) {
+	var binaryString = atob(base64String);
+	var charCodeArray = Array.from(binaryString).map((char) =>
+		char.charCodeAt(0),
+	);
+	var uintArray = new Uint8Array(charCodeArray);
+	return new TextDecoder('utf-8').decode(uintArray);
+}
+
 export async function getFileContent(
 	context: AppLoadContext,
 	path: string,
 ): Promise<string> {
-	const { ref, owner, repo } = getMetadata(context);
+	const { ref, owner, repo, language } = getMetadata(context);
 	const cache = getCache(context);
 	const cacheKey = `${ref}/${path}`;
 
@@ -54,7 +102,10 @@ export async function getFileContent(
 			repo,
 		});
 
-		content = atob(file.content);
+		// Japanese characters including UTF-8 are garbled, so convert to binary string before decoding
+		content = language.isDecodeUtf8
+			? base64DecodeUtf8(file.content)
+			: atob(file.content);
 		context.waitUntil(
 			cache.put(cacheKey, content, {
 				expirationTtl: 3600,