Sensai Izumi (泉繊細, Delicate Spring), who goes by the alias of Nanashi (名無し, Nameless), is an Avatar born from a Shinigami. She is the most powerful of the Avatar and is in control of the entirety of its Hive Mind, serving as a sort of queen. She was originally the Lieutenant of the 1st Division of the Gotei 13, however she became an Avatar and defected when she encountered the Pit of Reincarnation.