Worried about her son Masaru's lack of exercise, who is an indoor type who just lounges around at home every day after school, his mother Hiroko buys him a wrestling magazine that Masaru liked as a child and encourages him to exercise. When she tries to get Masaru, who is not interested, to do wrestling moves to get him to exercise, Masaru, who is of age, gets an erection, creating an awkward atmosphere... Masaru, who is the only one who gets an erection on his mother's body, touches his mother's crotch to relieve his embarrassment... Then his mother's crotch!