Two police detectives and SV2 investigate a series of mysterious acts of deadly destruction occuring in and around Tokyo Bay.

A pair of black-robed thieves who robbed many wealthy merchants in Edo one after another. One of them is a young woman who is called "Aoi no Kozo" because she always takes off her skin to show the tattoo on her back. The target of the robbers was the Kogi, and in particular, the big stores that were under the control of Hotta Bizen. Itami Hanzo, a Doshin known as "Kamisori Hanzo" discovers when he tracks down the Aoi no Kozo! What is the truth?!

Oniwaban is an organization that is composed of two ninja groups… Iga and Koga. This is a story of a secret spy who settled in Okazaki Joka town during the Seitoku period of General Ietsugu and his son who trained to be a Ninja.