Mizuki and her boyfriend Kazuya, who is about to get married, are a happy couple, but Mizuki has a strong sexual desire and secretly masturbates because her boyfriend's sex is unsatisfactory. Kazuya, who had always dreamed of studying abroad, invited Michael, a black man who had taken care of him, to his home and the three of them began living together. After Mizuki stumbled upon Michael's big cock, she was worried about it to the point of exceeding the limit.
