Jerga (ジェルガ, Jeruga) was the King of Gairadite 2,000 years ago, and commander of the Gairadite Demon King Subjugation Army.
As a human, Jerga had the appearance of a middle-aged man with a goatee.
Jerga held an intense and raging hatred towards demons. Blinded by this hatred, he was ignorant of the fact that he had turned into the very evil he accused the Demon King of being. His madness and insanity had no end, not wanting to rest until every last demon was annihilated from existence. He claimed that his hatred was that of all the humans, however, he had no problem killing multiple humans if it meant getting his revenge.
Jerga was Kanon's teacher, and the hero that preceded him. Due to the death of his wife and child, Jerga held a deep grudge against demons. On one occasion, the Demon King of Tyranny Anos Voldigoad, came to Azeshion to advocate peace with Kanon, but Jerga interrupted their conversation and attacked Anos, only to get severely injured.
Even after the four walls were made and the Demon King died, Jerga's hatred did not change. He believed that the battle would not end until the Demon King was completely dead, with that in mind, he set up the Hero Academy as a way to pass his resentment to the future generations. Kanon was strictly against the academy and its purpose, wanting peace with the demons instead. The tensions between the two almost resulted in a civil war between the humans, with each side having many allies. However, Jerga waited for Kanon to drop his guard, and had his allies kill him. In doing so, he made sure that his hatred could be passed on. He then altered the written history to make sure demons were viewed as cruel and evil, and even hid the fact that the Demon King willingly gave up his life to bring peace.
But he was still afraid that people would forget their hatred of demons. So, working with Nousgalia, The Father God, at the cost of his life, he transformed his source into two forms of magic, <Jerga> and <Eleonore>. He also managed to fuse his own source into <Asc>, resulting in anyone who uses it sharing his feelings of hatred and resentment towards demons.
After Diego is defeated and abandoned by his army, he casts <Jerga>, allowing Jerga to resurrect into a body made of Holy Magic. Lay attempts to kill him, but he explains that, as his body is made of holy magic, he can't be killed by the holy sword <Evansmana>. Jerga then attempts to detonate all 10,000 of the Zeshias with <Gavuel>, but he is stopped by the fused Sasha and Misha. He waits until they run out of magic power before trying again, only to be stopped by Anos who cast <Rivide> to stop the Zeshias' time.
Anos quickly destroys Jerga's source with <Bebesd>, but he reforms immediately. Jerga then uses <Asc> and <Jerga> to forcibly drain the hope of the subjugation force to imbue himself with holy armor and sword. He attempts to kill the group, but is distracted by Misa's <Fusca>. Jerga injures Anos, damaging his source, but Anos immediately recovers, having healed his source with <Agronemut>.
The fight is then interrupted by Lay, having gotten all 7 of his sources back. The hero cuts off Jerga's legs with Evansmana, surprising him while Anos reveals that he summoned the Demon King Castle Delsgade to the battlefield. The living magic is then cut down by Anos with <Venuzdonoa> and Lay with <Evansmana>, losing his power.
Anos explains that while his hatred went into <Jerga>, his desire for peace went into <Eleonore>, leaving him in emotional conflict. He also tells Jerga that he remembers killing his wife and son because they were tough opponents, and that he used <Silica> to reincarnate them afterwards. Just before killing Jerga with Venuzdonoa, Anos gives him a one-shelled necklace and uses <Silica> on him as well, as a way of saying he wishes him to reunite with his family after reincarnating.
- Immunity to Evansmana: Jerga is completely unaffected by Evansmana because a holy sword cannot cut something that is truly holy. Evansmana cannot destroy Jerga, nor can it sever his fate. However, this was made possible after Anos used Venuzdonoa, which can destroy reason and order.
- Conceptual Existence: After his source was turned into magic, Jerga became a world Order, a law or concept that makes up the world. In Jerga's case, it was the hatred towards demons. As long as the magic <Jerga> exists in the world, Jerga will never be destroyed. This is shown when Jerga reforms after being destroyed by Anos without leaving a trace.
- Sanctuary <Asc>: Great magic that can unite people's hearts and transform their hopes and wishes into magic power. Jerga fused himself with this magic to make any human that uses it become increasingly hostile against the demon race, manifesting as a disembodied voice telling them to kill the demons.
- Demon Judgement <Jerga>: Magic that was made for the express purpose of annihilating Anos. It was one of the two magics formed from Jerga's source; in particular, the part which contained his hatred towards demons. Since <Jerga> was fused with <Asc>, it was able to siphon enough magic to grant Jerga a new body and holy sword.
- Root Womb <Eleonore>: A humanoid-type magic made from the other half of his source. Because <Jerga> took all of his hate, <Eleonore> was what remained — the desire for the peace of his descendants, so that they don't experience the same hatred as he did.
- Ablaze Light Mortar Sanctuary <Theo Trias>: The holy magic power collected in <Sanctuary Asc> is turned into shells and shoot at once, this is the strongest light attribute magic of the heroes.
Weapons and Equipment
Holy Sword: A giant golden holy sword that is created through Demon Judgement <Jerga>. It can destroy a person's source, including Anos'. It was able to destroy Anos' Source of Perdition which can overcome its own perdition, except against specific and powerful holy weapons.
Jerga was willing to stake the future of humanity on Kanon, believing him to be the only one capable of defeating the Demon King of Tyranny. However, when he discovered hat Kanon had no intention of continuing the war, Jerga and his allies killed him.
Jerga utterly despises the demon race, especially the Demon King of Tyranny, Anos Voldigoad, whom he blames for the death of his wife and child. Anos, in return, replies that Jerga wasn't the only one that experienced tragedy, as Anos was born from his mother's corpse after she was killed by humans.
- Jerga somehow knows about <Venuzdonoa>, even though he never saw it 2,000 years ago and those who did died.