It's been a year since they started dating. Shinya is invited to her house for the first time, but he's so nervous that he arrives earlier than planned. He timidly presses the intercom, and it's not her but her mother, Yu, who greets him. Just then, she goes out shopping, so the two end up waiting together. Shinya can't help but be drawn to Yu, who exudes a naughty, adult sexiness. When Yu notices Shinya's gaze, he impulsively seduces her...