Hiroki is talking about the moon, which means that he's having an affair with his wife's husband. He's blushing, but he doesn't want to hurt his feelings, so he pushes his way into the bedroom, where Hiroki and his momoko are having sex. The two of them try to talk each other out of it, but they can't, because they're too close to the other's bedchambers to be able to hear each other.