It is possible to make withdrawals at mobile casinos using MasterCard in Japan. However, it is important to note that MasterCard only allows withdrawals to its debit cards. Furthermore, the MasterCard withdrawal process can be somewhat lengthy, as it usually takes around 3-5 business days for the withdrawal to be processed and the funds to arrive in the player's account.
Additionally, the withdrawal limit is usually much lower than the deposit limit, so it is important to check the casino’s terms and conditions before making a withdrawal. It is also important to note that some casinos may impose their own withdrawal limit, which is independent of the MasterCard limit.