I live with my big brother and my wife. I am always healed by the gentle smile of my sister-in-law Shiho. One day, my brother was on a business trip and I was alone at home with my sister-in-law Shiho. From there, the relationship between the two began ... I deliberately came in while taking a bath, changed my clothes in front of me, and finally slept in the same bed ... Naisho's forbidden relationship with his big brother continues today ...