You can restart the game from scratch by uninstalling the app and reinstalling it.

For the PC version, you must also delete your account in addition to reinstalling the app.
Please follow the steps below to delete your account.

1.) Tap the menu button (三) at the top-right corner of the Home screen and select [Settings].
2.) Next, select [Delete Account] from the Settings page.
3.) After carefully reading the disclaimer, enter [DELETE] in the text box and select [Request Deletion].