Senō Natsuru is your normal, everyday high school student. However, he's been chosen to be a Kämpfer, who's objective consists on fighting other Kämpfer with either guns, swords or magic. However, there's catch—first, you can't chose if you're a Kämpfer or not, and second, you must have the body of a girl to use your powers.
Five girls live in 19th century London, a city within the Albion Kingdom divided into east and west by a large wall. The girls serve as undercover spies enrolled as students at the prestigious Queen's Mayfair school. The girls make use of their individual abilities to remain active in the underground world of disguise, espionage, infiltration, and car chases.