High school student Mao was asked by her sister, who cannot have children, to carry a surrogate pregnancy. For the sake of her sister wanting a blood-related child, Mao decides to have sex with her brother-in-law. As Mao's young body is toyed with by her brother-in-law, she begins to feel pleasure. On a night when her sister is away on a trip, her brother-in-law releases his hidden perverted desires. In a room strewn with lewd SM goods, Mao is tied to a chair. After being made to drink an aphrodisiac, Mao is raped in a threesome involving her brother-in-law's friend... The fourth installment of the incest drama where familial love and sexual desire intertwine over 'surrogate pregnancy'！！
