Hayase Nagatoro  is one of the two main characters of the Don't Toy With Me, Miss Nagatoro manga series. She is a high school student who likes to tease and bully her Senpai, the other main character, although she secretly harbors strong feelings for him. Nagatoro is an energetic, athletic, popular and rather sadistic - but deep down very sweet - girl, often referred to as a "sadodere". She is part of a 'cool kids' clique together with her friends Gamo-chan, Yoshi and Sakura, and is a member of the swimming club, despite also having a liking for martial arts such as muay thai, boxing, capoeira and especially judo whom eventually lead her to join the judo club as well.

Her friends affectionately call her with the pet name "Hayacchi"  although this sometimes seems to be an annoyance to her.