Ryomen Sukuna more often called just Sukuna, is a mighty cursed spirit known as the undisputed King of Curses. He serves as one of the primary antagonists of the Jujutsu Kaisen series.

According to a legend, during the golden age of jujutsu over 1,000 years ago, Sukuna was an Imaginary Demon, though in truth was a human sorcerer, and other sorcerers gave their all to defeat him. After his death, he became a cursed spirit, and his curse was too strong for his body to be fully destroyed. Henceforth, his remains of 20 indestructible fingers, preserved in grave wax, traversed the ages as cursed objects, ever growing in power. In the present, Sukuna has been incarnated into Yuji Itadori due to the latter eating one of his cursed fingers, which contain his fragmented power.