Yoji returns to his hometown, but his brother and his wife seem to be on bad terms.He seems to be having trouble with his fertility policy.Yoji keeps a distance from him, but he accidentally peeps into his brother and his wife's activities...He can't take his eyes off the obscene appearance of his usually quiet sister-in-law, and Ai notices it.Ai, who wants to get pregnant no matter what, seduces Yoji if it is her brother's sperm.Yoji, who was swept away by her sister-in-law's dementia, who was drenched in sweat and encouraged her to ejaculate many times, finally released a large amount of semen into her vagina.