The entry for comment text. Some words (something like F-words) restricted by FC2.com. Also, to avoid spams, a comment which is written only in English would also be rejected by FC2.So, you would need to paste some Japanese texts with your English comment. Please use google translation.
A password for edit your comment later, and it also shows an auto-generated ID to specify unique user.That ID would be generated from a password irreversibly.You can left this as empty if you do not need.