One day, my boyfriend's best friend, Tatsuya, came over to the house we live in together. I had been drinking a lot and maybe I let my guard down. In front of Tatsuya who was sleeping, I had sex with my boyfriend as usual. I got even more excited thinking that he might be watching me, and even though I knew it was wrong, I couldn't stop myself. This is the record of the four days I had sex with my boyfriend's best friend while he was away.