Chisa, the stepmother, is married to her husband and lives with his son, Yoshio. Her husband is currently away on a work assignment, leaving the two alone together. Chisa struggles with her growing attraction toward Yoshio as a man, while Yoshio secretly fantasizes about spending the night with her and indulges in lewd daydreams with his friends. As their desires begin to converge, Chisa's lustful behavior unfolds—driven by her craving for a youthful body.