Near future. A global disaster called the "Cataclysm" ushers an age of chaos to the world. Countries collapse, metropolises which are spared the devastation of the meteorite impact are the new centres of command and control.

The Federation "Sanctum", ruled by the "Queens" enforces a despotism where female dominance is idealised. Males are persecuted against and are not allowed even the basest of occupations, they are forced to live in the outskirts slums.

One of Sanctum's cities, Astrea, maintains the subservience of males. The city's law enforcement "Grace", reigns over the city through fear and violence, its elite "Nightmare Raven" comprised solely of females who have sworn eternal devotion to the Empress.

Skirmishes between Nightmare Raven and men in the slums occur day and night, the weak can only hope to wait out the storm of violence with bated breath in the city's darkest corners.

A man rides into Astrea on a pitch-black motorcycle, his name is Kamui. Kamui's battle to subjugate the women of Nightmare Raven and liberate the oppressed males begins now.