Ja Wangnan is a Regular ascending the Tower with the aspiration to become its king. His origins remain veiled in enigma, yet he holds profound connections to Zahard, the Tower's ruler. Raised by a nanny who called him the "seed of the king," he represents the "biggest mistake" and a "fatal weak point" Zahard and the 10 Great Families sought to conceal. His Guide, Hwa Ryun, dubs him the "Prince of the Red Light District," hinting at potential illegitimacy or shame tied to Zahard. His name backwards reads "I am prince," and he employs "Yellow Prince" as a codename. He owns a ring identical to Karaka's, bearing Zahard's crest, implying a deeper familial or symbolic bond. Despite a youthful facade, he is remarkably old, having stalled for years in his early climb due to repeated test failures – memories he subconsciously buried to manage trauma. Wangnan displays fierce determination and idealism despite physical frailty compared to other Regulars. He champions perseverance, arguing the sole difference between successful climbers and himself is surrender. He dreams of forging a Tower where peaceful coexistence thrives under a "wider sky." Yet, he wrestles with guilt over endangering allies and acknowledges he might lie or kill to ascend, seeking forgiveness for such deeds. His charisma draws followers, forming Team Sweet and Sour, initially comprising Goseng, Miseng, Akraptor, Prince, and later Viole (Jyu Viole Grace). He feels the suffering and deaths of those around him acutely, especially after failures like a poor Shinsu-strengthening test ranking. His journey escalates upon meeting Viole on the 20th Floor. Wangnan recruits Viole into his team, recognizing his power but condemning FUG's exploitation. He declares his team's independence from FUG, the 10 Families, and Zahard, choosing an "Own Way." During the Hell Train arc, he masterminds a plan to capture Cassano to heal Horyang, serving as bait. Though savagely beaten by Cassano, he denounces Cassano's philosophy of sacrificing individuals for grand causes, declaring decent people never abandon those nearby for distant ideals. The mission succeeds with Akraptor's aid, only for Rachel to ambush them afterward. Akraptor sacrifices himself for Wangnan, and White consumes Prince. These losses shatter Wangnan, who vows to make Rachel "pay the price" for Akraptor's death. Wangnan possesses distinct traits: he wields Reel Inventory and Shinsu bombs resembling Poké Balls, and exhibits regenerative abilities verging on immortality, surviving lethal events like Yihwa's attack that killed others. He harbors significant knowledge of the Tower's secrets, and his climb is framed as the central axis of the overarching story.