Jiro returns to his hometown in the summer. He finds out that his brother and his wife are undergoing fertility treatment, and feels an awkward atmosphere... That night, Jiro happens to peek at his brother and his wife having sex, and is captivated by his sister-in-law Kana's intense and lewd behavior, which is unimaginable from her usual quiet appearance. Kana desperately wants to get pregnant, and begs Jiro, whose wife is in the stable period of her pregnancy, to cum inside her. Unable to resist the temptation of his sister-in-law, who is sweating and urging him to ejaculate, hiding from the eyes of her family, Jiro finally ejaculates deep into her vagina...