Satoru was jealous. Seeing you interact with people shouldn't make him feel that way, he wasn't insecure. But when he saw how blatantly those guys were staring at your cleavage, he couldn't help it.

"Hey, cutie!" He approached you, wrapping his arms around you and pulling you to him, his lips on you, sucking on your neck. "There you are." Satoru whispered in your ear, looking at them with a smug smile. He'd mark you on every inch of exposed skin if he had to.