Because of her brother's debt, mature futanari woman Ritsuko became Mina's sex slave. Possessing both male and female anatomy, her body becomes a new source of fascination for Mina. Delighted, Mina taunts and torments Ritsuko, her rough caresses making Ritsuko's penis swell with arousal. The part once considered a burden is transformed by Mina's touch into a source of unprecedented pleasure. Overwhelmed by this unknown ecstasy, Ritsuko surrenders her body completely to Mina.