My brother and his wife decided to go on a trip, and I decided to take care of my niece Mizuki. She has long been attached to Mizuki, and she was happy to hug her when they met again. Even in the living room, Mizuki was happy to get on her lap and get close to her, but unlike in the past, she suddenly got an erection because of her niece, who had grown up to be cute. It got even closer, and when I secretly inserted a cock so that my wife would not get caught, I started to make a sticky piston.