Set in 1949 in the fictional capital city of Teito, where aristocrats monopolize most of the wealth. K-20, a mysterious man with the ability to change his appearance frequently targets the rich for his theft. One day he manages to trick police into thinking a circus acrobat named Heikichi Endo is the real criminal, leaving it up to Endo to escape jail and prove his innocence. Meanwhile K-20 targets his next victim, Yoko Hashiba--an heiress whose fiance is Kogoro Akechi, the famous detective who arrested Endo. But Endo still has a score to settle, and picks a fight with K-20.