Amon (also spelled Aamon or Amaymon, along with many other variations) is a Marquis of Hell. He is the seventh of the 72 Goetic demons who governs forty infernal legions.
He appears as a wolf with a snake's tail who can breathe fire, or as a man with dog's teeth who is situated inside of a raven, or as a raven-headed man. Collin de Plancy took the artistic liberty of compressing Amon's two forms into one with the head of a dog-teethed raven, the body of a wolf, and a snake tail in place of its back legs. At the command of a mage, Amon may take the shape of man with a raven's head, having teeth of a canine. He tells of all things past and future. According to the Grand Grimoire, he is a direct subordinate of Satanachia.
He procures love and reconciles controversies between friends and foes. Some demonologists have associated his name with the Egyptian god Amun or with the god Ba‘al Hammon of Carthage.
As Amaymon or Amoymon he is said to be a Prince of Hell and King of either the West or East. Asmodeus and sometimes Gaap are said to be his servants. A silver ring is required to be worn on the middle finger when summoning him, as his deadly breath will kill the summoner otherwise.
Amon is the warden of the Third Sphere of the newly introduced Womb of Grief. Unlike the other bosses in the Womb of Grief, Alex defeats him before the protagonist can reach him. If the protagonist completes the Womb of Grief but chooses not to help Alex change the future, Alex empowers herself with the Third Fruit and attacks him alongside Shaytan and Amon.
A demon who appears before Gina in Naraku offering her power. He is killed by Walter in the Domain he sets up, but bites him and warns that the infection will make him hunger for power and seek out the power of demons, dissipating afterwards. The infection grants Walter inhuman strength and regeneration, spawning mouths, hands, arms, and tentacles from amputated limbs or just upon Walter's body. It's also causing him to see people as demons, such as the three Amaimons in Chapter 2, or hallucinating the demon's mouth and arms under Hugo's robes.
Later on, with the demon's "help", Walter escapes Mikado Castle and descends through Naraku, killing and eating the Minotaur in the process. After reaching Tokyo, Walter again catches sight of Amaimon in the mirrored surface of a cell phone. When attacked by Ashura-kai forces, the demon forcibly asserts control and kills the attackers, including Yaso-Magatsuhi. As time passes, Walter steadily loses control to Amaimon, becoming nearly bestial in combat.
After another brutal berserker rage, the tired Walter is approached by Hiruko, who is devoured through an Amaimon mouth in Walter's chest to create a new demon.