Amun

"Hey, kids, wanna see the ultimate unification of the multiverse and the absolute whiteness of the void that will follow?"

- Amun nonchalantly revealing his end goal Amun (アムン, Amun), known more fiercely as the Original Sin Demon (正罪魔, Seitsumima), is the mysterious ancient demon who essentially shaped human and demon history to its current state, being a prime factor in the Demon race's loss during the Dragon Civil War, Gehenna's creation, and indirectly being responsible for the death of the Dragon race, and millions more. It is a demon who possess the powerful ability to travel between parallel worlds, activating whenever it dies, replacing the current Amun for a randomly picked parallel world version, whom differs either slightly or extremely from the previous version, yet possesses the same end goal and shared memories. To distinguish between the different Amun and their identities, their names are followed by "The ___" (ザ, za ___)

Amun the Murderer
Amun the Murderer (アムン殺害者, Amun Satsugaisha)

Amun the Cross
Amun the Cross (アムン十字, Amun Juuji)

Trivia

 * Amun's concept is somewhat inspired by Demonbane from the Demonbane visual novel, and Funny Valentine from JoJo's Bizarre Adventure: Steel Ball Run, albeit toned down significantly.
 * Amun is the same demon whom Amon got his "first name" from.