In 2071, roughly fifty years after an accident with a hyperspace gateway made the Earth almost uninhabitable, humanity has colonized most of the rocky planets and moons of the Solar System. Amid a rising crime rate, the Inter Solar System Police (ISSP) set up a legalized contract system, in which registered bounty hunters, also referred to as "Cowboys", chase criminals and bring them in alive in return for a reward.
The Meiji Era was one of great renewal for Japan, where swords and killing were outlawed. However, many survivors from the time of Revolution still live, lurking in the shadows and waiting for a chance to use their killing blades again. Only Kenshin Himura, formerly one of the most brutal of killers, hopes to keep his swordsman's honor and still live in the new era.
Saya Kisaragi is an outwardly normal girl who serves as the shrine maiden to a country town; in reality, she is a skilled swordswoman charged by her father to defeat Elder Bairns, monsters who feed on human blood. As her battles grow more desperate and more people she cares for fall victim to the Elder Bairns, Saya begins finding faults in her reality, and eventually uncovers a disturbing truth about herself, the town and her surviving friends.
