Amazon Translateが日本語対応したので使ってみた ref: https://qiita.com/kojiisd/items/e2bc1b655524100511b8

file0.html

                <tr>
                    <td><label>Source Language: </label></td>
                    <td>
                        <select name="srcLang">
                            <option value="en" selected>English</option>
                            <option value="zh">Chinese (Simplified)</option>
                            <option value="fr">French</option>
                            <option value="de">German</option>
                            <option value="pt">Portuguese</option>
                            <option value="es">Spanish</option>
                            <option value="ja">Japanese</option>  /* 追加箇所 */
                        </select>
                    </td>
                </tr>
                <tr>
                    <td><label>Target Language: </label></td>
                    <td>
                        <select name="targetLang">
                            <option value="en" selected>English</option>
                            <option value="zh">Chinese (Simplified)</option>
                            <option value="fr">French</option>
                            <option value="de">German</option>
                            <option value="pt">Portuguese</option>
                            <option value="es">Spanish</option>
                            <option value="ja">Japanese</option>  /* 追加箇所 */
                        </select>
                    </td>
                </tr>