Sukuna

Sukuna (宿すく儺な Sukuna?) or Double-Faced Specter (両りょう面めん宿すく儺なRyōmen Sukuna?) is one of the main antagonists in Jujutsu Kaisen, and is the undisputed King of Curses.

History
According to the legend, Sukuna was a vicious demon with the appearance of a human who appeared during the golden prime era of sorcery 1,000 years ago. With immemseable power he would wrack untold havoc throughout the era and would constantly fight the shamans of old with his demonic abilities. Gaving their all to destroy him, they eventually defeat and killed him. After his death, they weren't even able to destroy his indestructible body and it crossed into the human world as cursed charms in the form of his severed body parts were scattered and lost through out the ages.

Centuries later, in 2018 ad of the modern era, one of his fingers reapeared and was being kept in an outdoor thermometer box at Sugisawa High School. The School's local Occult Club had taken the finger from the thermometer box and inexplicably removed the seal placed on it.

Personality
A sadistic enitiy, Sukuna enjoys the suffering of others immensely. Smiling with childlike glee to the possiblties of carnage and slaughter after awakening in the modern era and mockingly laughed at his host, Yuji Itadori's inability in saving his new found friend from a horrifying and mutilating death. He is also very greedy, and always wants to stay in control of the situation without caring about the consequences.