Uraume

Species: human
Age: 1000+
Gender: unknown
Hair color: white with a red-pink strip
Eye color: dark pink

Uraume is a recurring antagonist in Jujutsu Kaisen. They are a curse user from a thousand years ago who is a direct subordinate to Sukuna. They aligned themselves with Kenjaku to seal Satoru Gojo and revive Sukuna.

According to the Jujutsu Kaisen Official Fanbook,

Uraume has been by Sukuna's side since a thousand years ago. They are a human and sorcerer and are allowed to stand beside Sukuna because Uraume is very talent at cooking people, which Sukuna eats.
(Source: Jujutsu Kaisen Wikia, edited)