It was customary for my sisters to always come back to their parents' house at the same time. This year, that time came around again and I decided to visit them, but unlike my own house, I was unsure of where to stay and as I was walking down the hallway, I saw something I shouldn't have seen. My sister-in-law masturbating... This was the beginning of a secret that I couldn't tell my wife about... Although I felt Kokoro about the complicated incestuous relationship between my sister-in-law and brother, I lost myself in the pleasure and excitement...