September 1945, Tokyo. A post-war process is underway in the underbelly of this city which became a burnt wasteland. It is the extermination of the remnants of the human weapons "Unit 731". Saika, a young immortal girl soldier, with her subordinate Kankurou Konoe, a combat medic feared as the Grim Reaper, takes on the responsibility of killing her compatriots in order to gain her freedom. (Source: Kadokawa, translated)