Tatsuya, whose wife is about to give birth and has gone back to her parents' home, is busy with housework. He feels lonely in his days without anyone to talk to. Just then, his wife's sister, Maina, comes to check on him. Tatsuya is overjoyed to have someone to talk to again and welcomes Maina, but... Maina's true intention is his body. Maina suddenly barges into the bathroom. Tatsuya, with nowhere to escape, is left with no choice but to submit to her irresistible, firm, and fair breasts.
