Takechi Otoya is an extremely playful girl with a rather intrusive personality. She likes to tease others, but her actions are seen as borderline bullying.

Otoya has somewhat of an insane personality. Her obsession lies with her scissors, to the point where she carries a whole bag of them around on her waist. It is later revealed that outside of Myoujou Academy, Otoya has been dubbed as the "Jack the Ripper of the 21st Century", presumably because of her scissors. She is the first to attempt an attack on Haru, and demanded serial killer insurance as a reward from Nio if she were successful. However, she fails when Tokaku interjects and stalls long enough for Haru to shove poisonous plants in Otoya's mouth. Otoya collapses afterwards, and when the time limit passes by, Nio informs Otoya that she must drop out of the school.