It's so unnerving, but...Bowser seems to be right. The flames are licking up his hand, but without actually burning it. It's not enough for Izuku to be brave enough to stick his own hand in the flames, of course, but...almost enough.

Izuku will follow Bowser as he akes his way over to the water, keeping an eye on him just in case those flames suddenly spread. They may not burn him, but that doesn't mean they can't burn other things.

"What kinds of experiments have you been doing?" Izuku asks. "Other than, uh...putting your hands in it, I mean."