As spring break brings Masaki, Erina, Tetsu, and Shinobu to a private beach, initial seaside enjoyment gives way to secret discoveries that shatter all inhibitions. Erina's big boobs and enticing lactation become the center of attention in an atmosphere of mutual exhibitionism and partner-swapping teases, with the couples indulging in risky outdoor passions. The hentai builds through sensual blow job play and creampie releases to playful insults between Erina and Shinobu escalating into shared ecstasy, ending on a surprising note about marriage amid the debauchery.