A very tight half-sister

They've only been living together for a while, but the girl makes it very horny. She is his stepsister and met her only a couple of months ago. The first times he touched her ass she looked at him in surprise, but now it's a habit. At any moment he comes up to her and touches her tits or her ass... Sometimes he even masturbates in front of her. This time he goes further and puts his cock in her pussy. And he loves how tight it is.