Hajun is a supporting antagonist in the manga/anime series Record of Ragnarok.

He is the main antagonist of the Sixth Round and a minor antagonist in the Seventh Round and the Tenth Round of the Ragnarok Tournament.

Hajun is the Demon Lord of the Sixth Heaven who destroyed half of Helheim in ancient times and, after self-destructing due to his power, returned during the Ragnarok Tournament thanks to Beelzebub taking possession of Zerofuku. He is also the second Gods' representative of the Gods Fighters during the Sixth Round replacing Zerofuku, where he faces Buddha as the Humans' representative of the Einherjar.

Hajun is an ancient legendary Demon Lord infamous for destroying half of Netherworld/Helheim prior to Hades' rise as a monarch. Hajun would eventually succumb to his own power, resulting in his body collapsing on itself and exploding, leaving no trace of him ever existing and leading to dismissing him as a fairy tale. However, eons later, a powerful God known as Beelzebub eventually found his remains and converted them into a seed, which he planted in God of Misfortune known as Zerofuku, who in turn would split himself into Seven Lucky Gods.

During the Ragnarok Tournament, in which Buddha betrayed Gods to fight for Humanity in the Sixth Round, Seven Lucky Gods would merge back to Zerofuku. Unable to defeat his opponent, however, Zerofuku let go of his hatred for Buddha, only to be consumed by two serpentine dragons that came out of his body, turning him into an egg from which Hajun hatched.

Hajun apears to be a tall and muscular humanoid demon with a pair of curved buffalo-like horns in deep shade of red, as well as black eyes with golden irises and silver long hair. His muscle tissue is irregular, forming a collar around his neck, as well as several spike protrusions from his forearms, some of which appear to be covered in red organic armor.

Hajun is shown to be serious, relentless, arrogant and confident yet stoic and blunt, contrasting Zerofuku's self-loathing and miserable nature.