Miyatsuji sisters Kotono and Suzuyo attended Ikaruga High School, where their mother Kasumi served as chairperson. The two beautiful sisters had captivated the heart of one man - Souichi Kaneshiro. However, his attention was focused on school nurse Morisawa Maiko, and he was completely enthralled by her body... Kaneshiro, who would be expelled if he failed this upcoming exam, sneaked into the principal's office at Maiko's instigation. Unfortunately for him, Kotono caught him in the act. To silence her, Kaneshiro pounced on Kotono in the locker room, where she was changing into her swimsuit - her half-naked body now his to claim.