Yuhoshi's mother is Hirano Kyoko, a famous actress renowned for her popularity and talent. Having lost his father at an early age, Yuhoshi lives alone with the beautiful Kyoko, and his mother was the ideal woman for him. His feelings for her were so strong that Yuhoshi began masturbating when he saw Kyoko on TV. One day, Mayumi, Kyoko's older sister and aunt, saw him like that... And in order to satisfy Yuhoshi's twisted desires, Mayumi disguised herself as Kyoko and became Yuhoshi's "mama," providing sexual relief, but all Yuhoshi could think about was his mother, Kyoko...