In the anime and manga series Jujutsu Kaisen, the Prison Realm is a special grade cursed object and living barrier that can imprison anything or anyone inside an inescapable pocket dimension. It is made from the remains of the Buddhist Monk Genshin and is referred to as a "taboo object". The Prison Realm usually appears as a small red cube with numerous eyes covering all sides and is ordinarily completely wrapped in talismans when not being used. Once activated with the incantation "gate open," the Prison Realm separates into four cubes with a thin fleshy mass that contains a giant eye between them. It must be activated within four meters of its target in order to take hold, and when it does, it latches onto and fuses with the victim as though it were part of their own body, holding the new prisoner in place. After the user chants "gate close," the Prison Realm completely seals its victim within it, cutting them off from the outside world entirely. Time does not pass inside the Prison Realms pocket dimension, and the sealed individual is surrounded by dark skeletons and a dreary atmosphere. Only one person can be contained at any given time, and the Prison Realm cannot be used again unless the person within takes their own life.

In the series, Satoru Gojo, one of the main characters, is imprisoned in the Prison Realm during the Shibuya Incident. While trapped in the Prison Realm, Gojo acquires the ability to manipulate similar spaces, which he uses to shrink his domain, making it as small as a basketball. This not only limits Sukunas attacks but also weakens his abilities. However, unsealing Gojo from the Prison Realm is not an easy task, as he is a powerful sorcerer who has the potential to escape.