Tokyo is infested with demons, creatures of darkness and corruption. By ancient unspoken agreement, humans and these dark beings have always held themselves apart—until man’s depravity began to break down the barriers. At present, humans and demons collude to form gangs and corporations.

Though evil may be on the rise, those who still choose to walk the righteous path find themselves far from powerless. The government has formed the Taimanin, a group of ninjas who, while human, possess the strength to fight such nefarious foes.

Asagi Igawa is the strongest of these elites, but after one last mission against Oboro—the fallen ninja leader of the Oboro Ninja Troop—she plans to retire from her years of service to marry her lover Kyousuke Sawaki.

Yet her duty may not yet be done with Asagi, as her nemesis creeps back from the dead to seek vengeance…