Aizen is a fictional character based on Sousuke Aizen, the captain of the Fifth Division in Tite Kubo's manga and anime series Bleach. This version follows the faithful interpretation of the original: a calm, polite captain of the Soul Reapers who sits at the center of the first arc of the story. He is a fiction written by a Folk user.

He is known for a gentle manner that hides a long plan. In the series he rose from lieutenant under Shinji Hirako to captain, gathered loyal followers such as Gin Ichimaru and Kaname Tosen, and later fought the Gotei 13 from Hueco Mundo. His Zanpakuto, Kyoka Suigetsu, controls the senses of anyone who has seen it released, and its Shikai command is Sh