MANGA SPOILERS AHEAD
I love a good theory as much as the next person. Jujutsu Kaisen has risen in popularity by tenfold since the anime aired and with this popularity has come an increase in theories. As the story progresses especially in the manga, there’s questions viewers have that these theories aim to answer:
Why is Yuji Sukuna’s Vessel?
There’s a theory that Yuji can be Sukuna’s vessel because he’s linked to Sukuna.
Sukuna is an actual Japanese legend – he’s a being with 4 arms and two faces. In some places the legend says that Sukuna was a kind spirit who saved villagers, but in other places the legend says that Sukuna was evil and that he killed and tortured people.
Because in Jujutsu Kaisen Sukuna is presented as pure evil though, this has lead some viewers to speculate that the ‘kind’ side of Sukuna could be Yuji.
This theory explains that the evil side of Sukuna was sealed away in his 20 fingers while his good side reincarnates as Yuji. This is used to explain why Yuji is the ‘1 in 1 million’ who can act as Sukuna’s vessel and why Yuji has enhanced superhuman physical abilities even before he ate his first cursed finger.
Is Yuji a Cursed Womb Death Painting?
This theory is discussed HERE. I loved reading this article because it explains a few theories regarding this question and what we have learnt in the manga about Yuji, Choso, their relationship and Yuji’s parents.
What is Toji’s Cursed Spirit Worm?
Toji has a cursed spirit worm that he takes with him to hold his weapons. Although Toji can’t actually see the spirit since he has zero cursed energy, he can sense its presence with his heightened senses. There’s a sad theory I saw HERE made by Tumblr user kaitinumaki about why this cursed spirit stays with Toji.