The story involves a mystery case of power users around the world suddenly committing suicide one after another, in all cases after a strange fog appears at the scene. At a request from Ango Sakaguchi, the Armed Detective Agency head out to investigate Tatsuhiko Shibusawa, a power user who calls himself "collector," and a man suspected of being tied to the incident.

Lelouch, Suzaku and other young warriors battle in the late Tokugawa Shogunate era, where the power of Geass forced Japan to falsely open up their ports!!

The curtain rises on an alternate world tale of Code Geass!!

(Taken from Bandai Entertainment)