A top-secret organization under the National Public Safety Commission.
Two partners: one is part of the "Legal Group", those who complete the legal course, and the other is part of the "Parvenu Group", those who have a criminal record.
They investigate private cases.
Chigaya and Natsume, who both hide a secret dating back to their childhood.
Kei and Zakuro, who separated from their former partners and formed a new pair.
What's the truth behind the mysterious accidents they got involved in!?
Enjoy a suspense adventure with a fixed coupling setting!