The reason for the 5% fee is explained very well. They can't send from their normal bank, and have to transfer the funds via domestic transfer first. This makes two currency exchange fees at 2.5% each, which is a common currency exchange fee in Japanese banks. USD -> JPY -> USD. You are obliged to cover the bank fees (see the ToS). You can find the currency exchange fee the multi-currency trading FAQ.
Is it explained properly for a new user who creates an account and then sells some bitcoin, expecting to receive the proceeds? I believe that will be the question before the court in determining if there is a fraudulent inducement. Maybe I missed it, but the last time I looked there was not even a mention of the manual withdrawal and 5% fee on the main withdrawal process pages.
Those of us who read the forums or the IRC may discover these things, but those don't strike me as reasonable disclosure.