The Mizuhanome System is a sophisticated technology that enables users to enter one of the most fascinating realms in existence: the human mind. By utilizing "cognition particles" left at a crime scene by the perpetrator, detectives from the specialized police unit Kura can materialize a criminal's unconscious mind as a strange flow of thoughts within a virtual environment. Their objective is to navigate this psychological dimension, known as an "id well," to uncover the culprit's identity. Entry into id wells is not open to everyone; the requirement is that the individual must have personally committed murder. This applies to former detective Akihito Narihisago, who operates under the alias "Sakaido" within the id wells. Once a respected police officer, tragedy befell him, and he soon found himself on the wrong side of the law. Despite this, Narihisago continues to aid Kura from confinement. While his exceptional detective skills remain valuable for investigations, Narihisago realizes that the situation is more complex than it appears, as a far darker truth lies hidden behind what seems to be a series of unrelated murder cases.