Naoya Zenin comes back as a vengeful cursed spirit because of how he’s killed and how jujutsu sorcerers’ souls work in Jujutsu Kaisen’s lore.

Core reason he returns as a curse

In Jujutsu Kaisen, it’s stated that when a sorcerer is killed by non-jujutsu means (basically, “normally” instead of via jujutsu), their lingering cursed energy and grudge can cause them to reincarnate as a curse. Naoya is a strong Zenin clan sorcerer with a huge ego and intense resentment, especially toward Maki, so his death becomes the perfect setup for a powerful vengeful spirit.

Naoya is killed in a very “human” way, with no jujutsu technique used in the final blow, which triggers that rule about sorcerers becoming curses after such a death. Because he dies full of hatred, humiliation, and obsession with strength, his spirit doesn’t move on and instead twists into a curse driven almost entirely by revenge against Maki.

How his cursed form appears

When he first comes back, Naoya manifests in a “caterpillar” or worm-like cursed womb form with human arms, a grotesque in-between stage rather than a full humanoid curse. After he evolves, he becomes a chrysalis-like monster with a skull-like face and tendrils that act like limbs, far removed from his human appearance but clearly more dangerous.

This evolution also reflects his upgrade in power: as a full curse, his speed, strength, and Cursed Technique are amplified to the point where he surpasses even his father, who was famed as one of the fastest sorcerers. He retains his Projection Sorcery in curse form, so he is still insanely fast and technically skilled, just now boosted by the raw, hateful cursed energy of a vengeful spirit.

Why his curse is so strong

Several factors stack together to make Naoya’s cursed form exceptionally powerful:

  • He was already a high-level sorcerer, with strong innate talent and Projection Sorcery.
  • He’s from the Zenin clan, one of the big prestigious jujutsu families, so his “bloodline” gives him high potential.
  • His death is filled with humiliation and rage at losing to Maki, intensifying his grudge and thus his cursed energy as a vengeful spirit.

Fans often compare this to how powerful curses can form from single individuals with extreme emotions (like Yuta’s case with Rika), except Naoya’s is twisted around pride, misogyny, and obsession with strength.

In-story “scoop”: when he shows up

Naoya’s return as a curse is revealed during the Culling Game, when a talking worm-like curse appears before Maki and Noritoshi. Their shock and the curse’s mannerisms hint that it’s more than just a random spirit, and it’s quickly confirmed that this monster is actually Naoya, back specifically to hunt Maki down.

From there, the “scoop” is that he’s not just back but stronger than before, with his upgraded cursed form and enhanced Projection Sorcery turning him into one of the more terrifying speed-based threats of that phase of the story.

Information gathered from public forums or data available on the internet and portrayed here.