Mana reported that Kurumi Tokisaki is the most dangerousSpirit known, who has personally killed over 10,000 people (not including spacequake victims).

Kurumi Tokisaki used unstated and unexplained methods to personally transfer into Shido Itsuka's High School and classroom so she can get closer to him. Her purposes and reasons in this transfer are simple; consume Shido Itsuka and his ability. She somehow knew about Shidou and his ability and the fact that he knows about the existence of Spirits.