Yomi
A ghost without legs. She has brownish hair and is the teacher of "scary lessons." Spoiler She actually was bullied at her school. She finds a girl who is bullied too and becomes friends with her. Yomi pretends she's bullying her friend and throws her off the roof of the school. That was actually because she was planning tocause an explosion and kill everyone in the room and die too and she wanted her friend to be alive. The girl did survive but Yomi and the main bully don't. In the explosion, yomi's body got cut in half and they never found the downer part of her body. Yomi's ghost still remains in the school and it's said that, if you go to the school building exactly at 00:00 on the new year's night and bring her a gift she will grant you a wish.