There are 4 factions that exist in the world: Angels, Fallen Angels, Devils and Humans. Three factions are immortal beings fighting for their beliefs and power. Tooru (Oikawa) is the Great Devil King of the Underworld has taken in a new 'concubine' from the fallen angel faction, which angered the angels. The Angel Knight, Hajime (Iwaizumi), was sent to Tooru's side for a mission "You have my back right?" Tooru turns his head with a smile. "You can never achieve peace without bloodshed" "Long Live the Great King."