Board Thread:Questions and Answers/@comment-62.68.176.252-20170210193950/@comment-91.32.121.53-20170226155024

--V9/10 spoilers--

Due to an attack from Laughing Coffin's Johnny Black, Kirigaya Kazuto's heart stopped for several minutes, causing severe brain damage due to the lack of oxygen. Kikuoka Seijirou took him in and placed him in Underworld, a shortly a very advanced virtual reality allowing him to regenerate the damaged parts.