Kenjaku.

Kenjaku (羂けん索じゃく, Kenjaku?) is one of the primary antagonists of the Jujutsu Kaisen series. He is an ancient curse user who has existed for over a thousand years using his innate technique, which allows him to transplant his brain into other people to control them. He has inhabited different individuals throughout the centuries and assumed their identities.[2][3] Among those he has possessed include the blight of the Kamo clan who created the Cursed Womb: Death Paintings, Noritoshi Kamo,[3] the mother of Yuji Itadori, Kaori Itadori, and Suguru Geto, whose corpse Kenjaku is currently possessing to exploit his Cursed Spirit Manipulation.

Kenjaku is someone who has existed under countless identities for over a thousand years. There are even moments where he acts like whomever he's possessing unintentionally, such as when he caught himself suddenly acting like Suguru.[4] Despite constantly assuming different identities, Kenjaku retains a strong core personality. He is calm and calculating, rarely displaying signs of panic or distress and often has entire scenarios planned out in advance. At times he can appear cheerful, playful, and even charming, but he is a manipulative, and deeply egotistical individual who will stop at nothing to further his ambitions regardless of who he harms.

It is unknown what Kenjaku's original body looked like. He can only be distinguished by the stitches and scars that circle the top of his vessel's head. These are from the procedure required to transfer Kenjaku's brain, his only personal feature, into his host. Unlike a conventional brain, Kenjaku's has teeth.

In Suguru Geto's body, Kenjaku looks exactly as Suguru did during the Night Parade of a Hundred Demons, the day of his death.