Belialuin

, also known as the, is the homeland of the Boar's Sin of Gluttony, Merlin.

3,000 years ago
Belialuin was a city populated by wizards, who remained neutral during the Holy War between the Goddess Clan and the Demon Clan. It was a capital blessed with prosperity, where the superior wisemen of humanity lived. There, under the pretext of researching the ultimate magic, but really to serve as weapons against the higher ranking demons and goddesses, human children with aptitude for magic were experimented on as test subjects.

When a miraculous girl who possessed the Infinity power was born among them, the news soon spread in the realms of the goddesses and the demons and both parties tried to put the girl on their side to tip the balance of the war in their favor. The people of Belialuin opposed this, claiming that both the girl and her power were their property. However, against the wishes of her people, Merlin decided to negotiate with the gods of both clans, the Supreme Deity and the Demon King, and said she would follow the one who gave her the best blessing. Merlin somehow managed to deceive both gods to renege on them by accepting both blessings. Furious, the two gods unleashed their anger against Belialuin, cursing her with a fog of death for a thousand days and destroying it with a rain of fire and lightning. Merlin was able to escape unharmed, becoming the only survivor of Belialuin.

Defensive Battle for Liones arc
The Ten Commandments are aware of Belialuin history, and express shock that Merlin could be from there calling her "that survivor", implying some sort of great disaster befell it which only she survived.

Trivia

 * The name Belialuin appears to be stemming from the term "Belial" (or "Beliar") that first occurred in the Hebrew Bible, and later in Jewish and Christian texts to refer to the Devil personified.
 * In the DC Comics universe, Belial is also presented as the father of Merlin the Enchanter.