Megumi’s biological mother’s exact cause of death has not been officially revealed in Jujutsu Kaisen; the series only confirms that she died sometime shortly after his birth, and the rest is fan speculation and theory.

What’s actually confirmed (canon)

From the manga and author comments, fans generally agree on a few key points:

  • Megumi’s mom (often called “Mrs. Fushiguro” or “Mamaguro” by fans) is dead.
  • She died not long after Megumi was born.
  • Her death deeply affected Toji and pushed him back into his reckless, self-destructive lifestyle.
  • She was a non-sorcerer and represented a rare period of stability and happiness in Toji’s life.

None of these points specify how she died (illness, accident, murder, curse-related, etc.).

Popular fan theories about how she died

Since the story leaves this open, fans fill the gap with different theories:

  1. Illness or disease
    • Many fans assume she died of a mundane illness (like a serious disease), which matches how “quiet” and off-screen her death is treated.
 * This fits the idea that Toji’s life crumbled after losing a normal, kind partner.
  1. Complications related to childbirth
    • Some argue she may have died due to complications after Megumi’s birth, not during labor, since we do see Toji remember her holding baby Megumi.
 * This is still speculation, because the manga never states this outright.
  1. Injury, accident, or being killed
    • Other fans headcanon that she was killed (maybe because of Toji’s dangerous lifestyle or enemies) or died in an accident, but this is entirely fan imagination.

All of these are unconfirmed ; they’re just community guesses and headcanons.

What the community and forums say

Discussion threads and polls on forums and Q&A sites show how unclear this is:

  • Some posts casually claim “she died from illness,” but they rarely provide a solid manga citation and are usually mixing canon with interpretation.
  • Wiki and forum polls even let people “vote” on causes like disease, car accident, being killed, or “other,” which shows that there is no settled official answer.
  • Commenters often connect her death to:
    • Toji’s downward spiral.
    • The emotional trauma that shaped Megumi’s childhood.

So when people online say confidently “she died of X,” they’re usually blending canon background (she died after his birth, Toji fell apart) with their own preferred explanation.

So, what’s the latest understanding?

As of now, in 2026, the latest and most accurate way to put it is:

  • Official canon: Megumi’s mother died sometime soon after he was born; the cause is unknown/unstated.
  • Fandom consensus: Illness or some normal real-world cause is a common assumption, but it stays in the realm of theory, not confirmed fact.

If you see “She died from illness” stated as if it’s 100% canon, treat it as a popular theory rather than a hard, fully cited fact.

TL;DR:
We know Megumi’s mom is dead and that her death wrecked Toji’s life, but the story never officially explains how she died; every detailed cause you see online is speculation or fan headcanon, not explicit canon.

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