It's his way of showing sincerity!
"Place it on the side."
Gary Smith nodded his head, and Jenny Han, like a startled quail, carefully placed the coffee down. Her brown eyes were filled with curiosity as she observed the man reading quietly in front of her.
Though she didn't know whether he was a human...
However, he had come to her aid at her most desperate moment, just like a hero... or rather, a Demon King, easily wiping out their enemies.
Even though he didn't do this for her, Jenny Han was still very grateful to him.
Moreover, as she spent more time with him, she found that Mr. Door was not as terrifying as her grandfather had described; rather than devouring people and spreading curses, he would enjoy tranquility in his study room. He was cultured, approachable, and even...
Handsome!
After all, Gary Smith possessed good looks, which even Lisa Brown found surprising and thought was higher than any male Succubus, someone who could completely live off his looks.