My brother and his wife were going on a trip, so I decided to take care of my niece Mizuki. Mizuki had been fond of me since we were little, and was happy to see me again, hugging me. In the living room, Mizuki was happy to sit on my lap and get close to my niece, who had grown up to be so cute, but I got an erection when I noticed her change. At first, I thought she would scorn me, but she smiled and got even closer to me. I secretly inserted my penis so my wife wouldn't find out, and she started to thrust it in and out.