Yusuke Mizusawa was thinking about wanting a girlfriend with big breasts.One day, a friend introduced him to a girl with big breasts. ``My name is Rena Toyohara.Will you be my private tutor?'' Yusuke was invited to the Toyohara family to hear the details, and what he saw there was a man with bigger breasts than his daughter. It was Rena's mother Mizuki. Whether she knows about Yusuke's love for big breasts or not, Rena invites her to come without a bra and in skimpy clothes even when she's studying. Unable to resist, Yusuke begins to fondle her big breasts over her clothes...