There existed an ancient,
unspoken rule of non-interference betweenhumans and demons,
but as humanity descended into decadence,the rule has fallen to obsolesce;
it was the time of chaos, where evil syndicates of man and fiend roamed in the darkness.

But those who sought the righteous path were not hopeless.
The government established an organization of ninjas to fight against the evil.

They were known as the Taimanins.

In order to fight against worldwide terrorism and demonic threats,
a Taimanin task force is established. Their first mission is to retrieve
a bio-weapon stolen from the UFS base in Japan.

Things take an unanticipated turn, however, as an unexpected ally joins the task force,
and an equally unforeseen enemy approaches them.

The enemy is said to be related to Igawa Asagi, the Almighty Taimanin...