Naoya Zen’in was born the youngest son of Naobito Zen’in, the 28th head of the Zen’in clan, and was recognized from an early age as a prodigy. He inherited the clan’s hereditary technique, Projection Sorcery, a rare and deadly ability passed down through the family. Constant praise for his talent and status within the rigid hierarchy of the Zen’in clan shaped his identity, instilling in him a belief that strength, lineage, and traditional authority defined one’s worth.

Raised in this environment, Naoya developed an arrogant and condescending personality. He looked down on anyone he considered weak, particularly men he deemed inferior and women whom he viewed as inherently subordinate. He embraced a deeply patriarchal worldview; he regarded women as existing to serve men and dismissed those who sought power or agency as failures. This misogyny was especially directed at his cousins Maki and Mai Zen’in, whom he bullied and belittled for their lack of cursed energy and for challenging the clan’s norms.

Despite his disdain for weakness, Naoya held a peculiar admiration for Toji Fushiguro who he first wanted make fun if quickly changed his mind when Toji just walked oast him without meeting their eyes that day changed Naoya as long as he lived. Toji’s overwhelming physical strength without cursed energy contradicted much of the Zen’in clan’s traditional values, yet Naoya respected the raw power Toji embodied and saw him as someone who understood true strength. Naoya also valued strength in the mold of Satoru Gojo, whose power placed him at the pinnacle of jujutsu sorcery, though Naoya’s respect was tied to their perceived strength rather than personal affinity.

Naoya’s contempt extended to his older brothers, whom he regarded as inferior and useless, believing their reliance on cursed tools or conventional approaches marked them weak. He saw himself as the rightful heir to the Zen’in leadership, destined to embody and enforce the clan’s rigid ideals.

As an adult, Naoya became a Special Grade 1 sorcerer and served as head of the Hei, the clan’s elite combat unit. His life and worldview were driven by an obsession with status, strength, and maintaining a hierarchy that placed himself at the top.