Manabu, who has reached the age of a man, has begun to worry about his mother-in-law, Kaoru. She is 178cm tall and has F-cup big breasts... Her charm as a woman, which the girls in her class don't have, and the gentle way she treats Gaku, attracts the love of Gaku, who is not related by blood, even though she is her son. .One day, Kaoru comes home from mama-san volleyball practice and takes a shower as usual.When Manabu sees the situation, he sneaks into the dressing room and picks up the clothes Kaoru took off.Manabu involuntarily indulges in delusions when he sees sweat soaked practice clothes and fragrant panties.Then, the bathroom door suddenly opens, and Kaoru sees what's going on.