There existed an ancient,
unspoken rule of non-interference between humans and demons,
but as the humanity descends into decadande, the rule is now obsolete;
it is the darkest time, with the criminal syndicates pulling the strings.

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

They were known as the taimanins.

In order to fight against the international terrorism and demonic threats,
a taimanin task force is established.
Their first mission is to retrieve the bio-weapon that was stolen from
UFS base in Japanese territory.

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

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