~~The following program contains adult themes and scenes of violence and sexual assault that may not be suitable for some viewers and is inappropriate for children. The content is intended for mature audiences only.~~

Centuries ago, vicious and bloodthirsty demons who were immune to all manner of weaponry plagued mankind. Humanity's cries for help brought forth the Idaten; battle deities who would use their incredible speed to hunt the demons down, and then seal them away. In the following 800 years of peace, the Idaten have not had any enemies to fight. But that is about to change...
Grandfather, it seems like 800 
years of peace was too long...
...جدّي، يبدو أنّ 800 عام من السّلام كان طويلاً جداً
Großvater, 800 Jahre Frieden
waren wohl eine zu lange Zeit.
Abuelo,
Abuelo,
Grand-père,
Nonno, pare che 800 anni di pace
si siano rivelati troppi...
Avô, sinto que esses 800 anos
de paz foram longos demais...
Дедушка... Восемьсот лет мира —
это слишком долго...