pu·er·ile: immature; childish.

"Welcome to Sooman Academy. As long as you don't get gum on the floors or just generally anywhere, we should get along. Good luck, buddy," the janitor flashed a lopsided grin and ruffled his hair good-naturedly as she turned back to brandishing her mop/legendary sword with a few kindergartners. All he could remember was the foreign feeling in the pit of his stomach, the heat suffusing his cheeks and who the hell does she think she is?

Yifan is Sooman Academy's Headmaster Wu. But the janitor, Amber, seems to know more about how to run a school than he does.