in jujutsu kaisen, there are curses that are manifested by negative emotions that attack humans, and only a certain bunch of humans can see curses, and a few in those bunch are sorcerers, who can used cursed energy against curses, with their cursed techniques, which can be anything. there are big families of strong sorcerers like the gojo family, which gojo satoru comes from, the strongest sorcerer, and the most powerful curse, ryomen sukuna, who has a vessel named yuji itadori