Keiko lives with her husband's stepson Yoshio while his second husband is away on a business trip overseas. Although she knows she shouldn't think of Yoshio as a man, as he has recently become more muscular, she can't stop thinking about him. Yoshio, too, imagines Keiko being seduced by her classmates and indulging in carnal desires, and goes mad with jealousy. And then, the two finally confirm their love for each other. And then...