Netflix.
The website for the anime describes the series:
In a world powered by advanced technology, crime and action sweep through the archipelagic nation of cremona. Chief among the major players is “Killer B” - a serial killer who has thrown the city into chaos. The stories of Koku, the protagonist, Keith, a legendary investigator of the Royal Investigation Service, and a mysterious criminal organization intertwine on the path to reach their objectives. A wide variety of unforgettable characters surround them on the journey, as they attempt to stop a chain of horrific crimes in this suspense drama.
Nakazawa and