Yoji returns to his hometown, but his older brother and his wife seem to be having some trouble... They seem to be arguing over the policy for fertility treatment. Yoji keeps his distance, but by chance he peeks at his brother and his wife having sex... He can't take his eyes off his normally demure sister-in-law's lewd appearance, and Ai notices him. Ai, who desperately wants to get pregnant, seduces Yoji by offering her brother's sperm. Yoji is carried away by his sister-in-law's lewd behavior as she urges him to ejaculate over and over again while covered in sweat, and finally releases a large amount of semen into the depths of her vagina...