He sticks out his tongue. He's not jealous. Some day soon he might get the courage to ask Yako to wash his back for him. Then they'll find out who the jealous one is!!

"Too bad you're moving out then! I'm not coming all the way over to your place to wash your back!"

The truth is that this kind of laughing and teasing is just what he needs in order to deal with the fact that Sugata is actually leaving him.