Yusuke Mizusawa is worried about wanting a girlfriend with big breasts.One day, a friend introduces 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 keeps asking her out wearing skimpy clothes and no bra, even when she's studying. Unable to resist, Yusuke begins to fondle her big breasts over her clothes...