The narrative is set within the official Code Geass timeline of the anime, though in a different era. The protagonist, Renya, is a 17-year-old boy who wields a mechanical left arm and shuriken as his preferred weapons. The plot commences when Renya meets a mysterious witch named "Reifū C.C.", who appears perpetually young. C.C. has arrived in Japan during the historical Edo period to find a new partner for a covenant. Concurrently, a mysterious man bearing a striking resemblance to Lelouch from the original anime also appears, his intentions unknown.