YOU SAID:

You're going to Japan? Can I come?

INTO JAPANESE

日本に行くの？来てもいい？

BACK INTO ENGLISH

Are you going to Japan? May I come?

INTO JAPANESE

日本に行きますか？来てもいいですか。

BACK INTO ENGLISH

Do you go to Japan? May I come?

INTO JAPANESE

日本に行きますか？来てもいいですか。

BACK INTO ENGLISH

Do you go to Japan? May I come?