Rouka Numachi is a former basketball player whose broken leg ruined her athletic career forever. She was a former athletic rival of Suruga Kanbaru. After her injury ruined her life, she gained an interest in collecting misfortune which eventually turned into collecting devil body parts. Rouka is a girl of high-school age, with light brown hair and eyes. Her wavy hair is left unkempt, flows to her shoulders, and has a pair of locks that curl inwards from the back of her head, resembling a devil's horns. Because of her background, Rouka develops an obsession with misfortune, even at a young age. As a grade school pupil, she often puts herself in a pedestal by comparing her talent with the misfortune of others. However, after her life-changing injury, this eventually motivates her to collect the misfortunes of other people, justifying it as a way to ascertain that other people are more unfortunate than her.