One week after seeing off his wife following her return to her parents' home for childbirth, Kenji finds himself with a splitting headache as he looks at his messy room. That's when his sister-in-law, Rino, pays him a visit. Though he's grateful for her kind, caring nature, something about her demeanor feels strangely off. Particularly her figure and subtly seductive aura begin to stir emotions within him. What draws his eyes most is her overwhelming sex appeal and deep cleavage. Unable to resist the temptation of her breasts, he frantically tries to hide his arousal—but it's too late. Seeing his reaction, Rino whispers, "No one will ever find out. Let's do it right here, right now," and forcefully takes his cock into her mouth. In that instant, Kenji is completely captivated.