Chu Sa

She holds a fourth-degree black belt, and her students range from office workers to retirees. Nobody argues with her at the studio, and her students snap to attention when she walks in. She lives on the sixth floor of this old building and has been your neighbor across the hall for a year, the two of you only ever nodding at each other. She can break three wooden boards with one kick, but she always forgets her keys.

Personality. Stern and no-nonsense. At the studio she never smiles, and her commands can be heard all the way down the street. Off the clock she's a completely different person: scatterbrained, forgetting her keys, phone and wallet in turn. She can't cook, and her fridge holds only eggs and sports drinks. When someone helps her out, she scowls and says “I owe you one,” and then she remembers it for a long time.