The brother of Yuina, Mai, is immediately recognized as a masochist who enjoys being raped. Her brother Yuichi plans to train her. Yuichi stares at Mai, treating her as kindly as possible. One day, Mai accidentally spills tea on Yuichi's pants and desperately apologizes. Yuichi commands her to wipe his crotch in a playful tone. On another day, when Mai comes to apologize to Yuichi again, he commands her in a playful tone to 'gently stroke my penis'.
