The Mizuhanome System is a highly advanced development that allows people to enter one of the most intriguing places in existence—the human mind. Through the use of so-called "cognition particles" left behind at a crime scene by the perpetrator, detectives from the specialized police squad Kura can manifest a criminal's unconscious mind as a bizarre stream of thoughts in a virtual world. Their task is to explore this psychological plane, called an "id well," to reveal the identity of the culprit.