Item from Jujutsu Kaisen by Gege Akutami
A living barrier cursed object capable of sealing anything within an inescapable pocket dimension — the artifact used to seal Gojo Satoru during the Shibuya Incident.
The Prison Realm is a Special Grade cursed object and one of the most powerful sealing tools in existence. It creates a pocket dimension from which escape is considered impossible by conventional means. The activation condition is deceptively simple: the target must remain within a certain range for one minute. But against Gojo Satoru — a man who perceives everything with the Six Eyes — holding his attention for sixty seconds required Kenjaku to appear wearing the face of Gojo's dead best friend, Geto Suguru. The seal worked. Gojo was trapped inside the Prison Realm from the Shibuya Incident until the sorcerers found a way to open it using Angel's cursed technique, Jacob's Ladder, which can extinguish any cursed technique — including the Prison Realm's. The cube is both a weapon and a prison, and its existence proved that even the strongest sorcerer alive is not invincible.
A small cube roughly the size of a fist, covered in a fleshy, organic-looking membrane with a single grotesque eye on one face. When activated, it unfolds into a massive boundary that drags its target into an internal dimension. The cube pulses with cursed energy and seems almost alive — because it is, containing the remnants of the Buddhist monk Genshin.
Also known as: Prison Realm, the Prison Realm, the cube, Gokumonkyou