Eight hundred years ago a race of deities called the Idaten answered humanity's prayers and crushed the demons that nearly wiped it out, then sealed what remained and settled into a long peace. In the present, a younger generation of Idaten trains under Rin, the last survivor of that ancient war, knowing almost nothing of real combat. When the old demons begin to stir again, fighters like the relentless Hayato find their easy days of peace coming to an end.