The Special Investigation Unit is a secret force of specialists in various fields. The unit is under the direct control of the head of the Tokyo Metropolitan Police Department Security Bureau. Its members include investigator Inami Akira who sustained serious trauma in a special mission during the time he was in the Self-Defence Forces: and Tamura Saburo who was ordered to transfer from the Public Security Department Foreign Affairs Division in the wake of some incident and was later picked out by the Special Investigation Unit. These men will find themselves confronting irregular cases that will shake up the country.