The series follows Ryou as he moves in with his new step-mother, Mutsuki, and his incredibly busty step-sister, Mayu. An instant, overwhelming lust sparks between the step-siblings. The story arc chronicles their journey from shy, stolen glances to a full-blown, passionate incestuous affair. Their relationship begins with Ryou catching Mayu in moments of private self-pleasure, fantasizing about his cock. This tension explodes into raw, forbidden sex, with Ryou relentlessly fucking his step-sister's tight, wet pussy in every conceivable position. He buries his face between her massive, milky tits, gets sloppy blowjobs, and repeatedly fills her womb with his hot cum. Their secret affair is eventually discovered by their mother, Mutsuki, who, instead of stopping them, encourages their carnal relationship and eagerly joins them for debauched and sweaty threesomes, solidifying their new life as a completely sex-crazed family.