A new detective in the Mobile Investigative Unit (known as "MIU") of the Tokyo Metropolitan Police Department who does not trust other people works with an inexperienced detective and attempts to solve cases within 24 hours.

The MIU, Mobile Investigation Unit, is the Tokyo Metropolitan Police Department (MPD) Criminal Unit's first responders for initial crime investigations. Working round the clock, every MIU team only has up to four days to resolve each case, after which the case will be transferred to the MPD's other specialized investigation units.