They would probably take without returning. He didn't even know the two of them; once they took the spirit crystals, would they really return them to him? Absolutely not. Besides, he didn't even have any spirit crystals on him in the first place.
"I don't have any spirit crystals."
"You don't? Kid, I'm trying to reason with you and be polite, so you'd better know what's good for you. Otherwise, don't blame me for tearing your mouth apart."
Chapter 720