yude.jp/pages/tos.js

// Base layout
import Layout from "./components/Layout"

// i18n
import { useTranslation, useLanguageQuery, LanguageSwitcher } from 'next-export-i18n';

// Next.js, React
import { useRouter } from 'next/router'
import React from "react"

// React Markdown
import ReactMarkdown from "react-markdown"
import gfm from 'remark-gfm';
import ja from '../docs/tos/ja.md'
import en from '../docs/tos/en.md'

export default function Tos(props) {
    const { t } = useTranslation();
    const [query] = useLanguageQuery();
    
    if (!query) {
      return <p>Loading...</p>
    } else {
      return (
          <Layout title={t('tos')}>
          <div>
            {query["lang"] === 'ja' ? (
              <ReactMarkdown plugins={[gfm]}>
                  {ja}
              </ReactMarkdown>
            ) : (
              <ReactMarkdown plugins={[gfm]}>
                  {en}
              </ReactMarkdown>
            )}
          </div>
          </Layout>
          )
    }
  }