You can choose either an English or Japanese site from General Settings
1. Go to 'Site Management' ＞ 'Settings'＞ Check 'This site is multilingual'
2. Click 'Save' and you will see US and Japanese flags at the bottom.
You can select up to three languages from a dropdown list that includes 35 languages. For example, Japanese, Chinese, Russian, etc.
You can do this from the editor menu on the left, or in the upper right under ‘Admin’ after selecting it.