Mio is filled with guilt towards her husband and anxiety about her pregnancy after making a one-night mistake with a man who was her classmate at the class reunion. My brother-in-law, Takashi, who happened to come to Tokyo and came to stay, noticed that Mio was strange and began to explore. "According to what I heard from my brother, my sister-in-law seems to be worried about getting pregnant, even though there shouldn't be much married life at night. Maybe it's cheating..." Takashi, who had his eyes on Mio from the first time they met. However, he approached Mio about it...