Nigredo

The area guardian of the ground floor of the "Frozen Prison" located on the fifth floor. A magic caster specialized in information gathering.

Created by the same creator as Albedo as her elder sister, they are set up and recognize each other as sisters. Her appearance is that of a widow in black mourning clothes with long black hair, and while her facial features are well-formed, her face is exposed without skin, giving her a bizarre appearance.

Her personality is relatively normal, but she cannot engage in conversation without first performing a horror-themed skit, crafted by her creator, that portrays her as a "monster seeking a dead child."