Nanno

A girl with mysterious powers and an enigmatic origin. Nanno serves as a both guide and punisher to humans who hide secrets or want something without thinking of the consequences. Not much is known about her other than she is a teenager who doesn't age. Nanno is revealed to be an immortal entity that has the power to expose the lies and misdeeds of each faculty at every turn. Nanno is neither good nor evil in her crusade as she seems to punish everyone equally. Nanno prefers taking her time and planning out the appropriate punishments to the tormentors and offenders before she ends her games. Nanno's outfit consists of her short medium-length, bowl-cut/bob hairstyle with bangs, female school uniform, and evil inhuman-like cackle. She draws similarities to Tomie, which was credited as an inspiration for the role, according to Amatayakul.

(Source: Wikipedia)