Park Mujin, originally named Park Mubong, is a former Korean National Assembly member and elite fighter of The Six. He organized the God of High School tournament and changed his name seventeen years prior to the main events, deeming his birth name "lame". Standing 187 cm tall with a slim build, sharp black eyes pierce beneath narrow eye bags, framed by an X-shaped forehead scar from a battle with Jin Taejin. His hair defiantly forms horn-like tufts despite gel, and his signature attire is a black suit over an orange floral Hawaiian shirt, often paired with a zen-beaded necklace featuring a cross – a memento linked to Sang Mansuk.

Initially ambitious and morally ambiguous, Mujin displays ruthless pragmatism, exemplified by destroying an island to eliminate an obstructive associate. He possesses strategic cunning and patience, enduring public humiliation for long-term aims. Glimmers of compassion surface, such as sparing Jin Mori for honesty or funding protagonists' legal exoneration. However, his personality darkens significantly after becoming world president post-Ragnarök, growing increasingly cruel and cowardly, willing to sacrifice non-combatants to prepare humanity against divine threats. This culminates in his transformation into the Supreme God, rendering him emotionally detached, jaded, and merciless, viewing humanity as obsolete and planning its eradication. A complex appreciation for blunt honesty in others persists.

Mujin joined The Six at eighteen as a prodigy, though Jin Taejin defeated him, leaving the scar and igniting a lasting rivalry. A shaman prophesied he would become a "king who revolutionizes the world". His hatred for gods solidified after Sang Mansuk died at Beelzebub's hands. Seventeen years after Ragnarök, he used propaganda to rise to world president, only to be ousted when Park Ilpyo exposed his atrocities. During his final battle with Jin Mori, his betrayal of Mori and framing of Mori's grandfather were revealed, cementing his legacy as history's "greatest villain".

His abilities escalate dramatically: early Borrowed Power, Longinus Hand, grants gravity manipulation capable of flattening islands or planetary assaults. Post-Ragnarök, he wields Project Wi-Fi, a prosthetic arm countering powers like Satan's. As Supreme God, he gains reality-warping authority, ignoring laws like the Taboo (restricting human-god conflict) and Tam (reality-bending energy). His arsenal expands to the Eight Letters of Tathagata, including the Mandala (durability-ignoring dagger), Diamond Sutra (soul-vaporizing bell), and Blade of Tathagata (regeneration-negating sword). He absorbs Satan's heart for additional powers and commands abilities like paralysis, biological manipulation, and high-godly regeneration. His supreme state grants near-invincibility, resisting layered attacks involving probability, physics, and future-sight.

Narratively, Mujin stands as the antithesis of Jin Mori—a human ascending to godhood versus a god experiencing humanity. His drive to protect "Generation X" involves proactive measures like sealing Tathagata and later rebooting humanity into a "superior species" using the Supreme God's power. His final act revives Tathagata within himself to destroy existing humanity, leading to defeat by Mori. In his dying moments, he acknowledges his foolishness and hypocrisy, accepting his role in perpetuating cycles of violence before fading.