In Jujutsu Kaisen, all living beings exude energy called Cursed Energy (呪力, Juryoku), which arises from negative emotions that naturally flow through the body. Ordinary people are unable to control this flow in their bodies. As a result, they continually lose Cursed Energy, resulting in the birth of Curses (呪い, Noroi), a race of spiritual beings whose primary desire is to cause harm to humanity. These Curses are depicted as grotesque monsters: onryō (vengeful spirits), yūrei (ghosts), and yōkai.

Jujutsu Sorcerers (呪術師, Jujutsushi, lit. "Cursed Technique Masters" or "Shamans") are people who have the ability to control the flow of Cursed Energy in their bodies, allowing them to use it as they wish and reduce its release. High-level Sorcerers and Cursers can refine this energy and use it to perform Cursed Techniques (呪術式, Jujutsushiki), which tend to be unique to the user or their family. An advanced form of Cursed Technique is Domain Expansion (領域展開, Ryōiki Tenkai), in which users construct a pocket dimension of varying size. Within the Domain, all of their attacks are guaranteed to hit and increase in strength.