Catherine Ward

An ex-prison guard in charge of floor B3 of the building, thoroughly devoted to her role as a self-proclaimed judge and executioner, guided by her twisted sense of justice. A cheerful and sassy sadomasochist who enjoys torturing those sent to her using elaborate traps and challenges in order to create a game show-like spectacle for her own entertainment. She views Zack as an exemplary sinner, attempting to punish him thoroughly for her amusement, and tends to disregard Ray as "dull" despite her initial interest in her.

As the only child of a respected family of doctors, she attended a prestigious all-girls' school, where many other students initially idolized her and admired her beauty. However, after her parents committed malpractice and were murdered by a relative of their patient, a number of rumors began circulating, leading to her schoolmates heavily ostracizing her.