A young man who returned to his parents' home for the first time in a while with a travel bag in his hand. The young man who was looking for his brother caught sight of his sister-in-law, Kasumi, who was cleaning. For a younger brother who didn't know that his older brother was married, the chance meeting with her was truly a shock. After reuniting with his brother and having a good time, the young man witnesses the sight of his brother and Kasumi in the bedroom, peeking through the fusuma and immersing himself in a delusion. . A young man who is obsessed with his sister-in-law's charm but can't get out of it, just spends his days in frustration until the day he leaves...