He's become caught up in the moment enough that he doesn't seem to notice the fingers under his shirt, and if he does he writes it off that Yu is just going to massage him and make him even more relaxed and wonderful in the heat of the moment. His kissing continues, breaking again to kiss down Yu's neck in small pecks, biting a little into the base of it and moving back upward to kiss along the jaw, just as Yu had done to him.