If you are already logged in, go to the picture on the upper left(Side menu) -> [Settings] -> [Account information]. You will be seeing the account you signed up for.
However if you signed up by Facebook account, we are unable to access to your ID or password. So you have to check from Facebook for that information.
If you are unable to log in, please send us your nickname, guessed ID or your date of birth via button below. We will help you as fast as we can!