Humans are in desperate need of a trump card. They complete the Reincarnation Spell to summon powerful warriors from another world to help them defeat the demons. However, instead of heroes being summoned, the Reincarnation Spell was strong enough to release the seal that trapped the most powerful race within the demonic species. The Nenniaidae. They are unearthly beautiful women with seemingly bottomless amounts of mana. Exclusive to a Nenniaidae , these demons possess both the male and female reproductive organs.

They've lucked out in two ways; only a single Nenniaidae was released, and two, our protagonist, is controlling its body. A body that can be described as the typification of elegance, but with such scary power, she can be dubbed the embodiment of destruction. Due to the latter circumstance, mankind has evaded complete extinction. He- or now she- helps the humans fight against the Demon Lord's army to stop their plan to rule the world.