Overview:

A port city located on an island in East Asia… Koto. Divided into thirteen administrative districts, beneath Koto’s bustling surface lies a dark underbelly comprised of slums, black markets, cults, and assassins…
And then one day, the twelve most powerful gangs suddenly vanished, leaving only the Kyoukakai Association, which consists of a mere two members: a white-haired girl and… a penguin.