The unfolding of the Shibuya Incident in Jujutsu Kaisen hinged on the removal of Gojo from the equation, resulting in the tragic demise of numerous characters. The Prison Realm, a cursed object of significant consequence, played a pivotal role in orchestrating the events of the Shibuya Incident. Pseudo-Geto, employing meticulous planning and an ingenious strategy, successfully ensnared Gojo within the confines of the Prison Realm, capitalizing on his vulnerability.
In Jujutsu Kaisen, the entirety of the Shibuya Incident transpired due to Gojo's absence, leading to the loss of thousands of innocent lives and the demise of beloved characters. Despite his status as the most formidable sorcerer in the modern era, Gojo found himself subject to the rules of Jujutsu, as demonstrated in recent episodes of the anime. Pseudo-Geto's careful planning proved instrumental in immobilizing Gojo.
The catalyst for Gojo's removal and the subsequent unfolding of the Shibuya Incident was the existence of the Prison Realm. As a crucial element in the series' most significant arc, this cursed object emerges as one of the paramount entities in the Jujutsu Kaisen narrative. Exploring the significance of the Prison Realm sheds light on its pivotal role in shaping the course of the story.
What is the Prison Realm?
The Prison Realm is a highly powerful Special Grade cursed object that can effectively trap anyone within itself for as long as needed. It is a red cube that is covered in eyes on all sides and is small enough to fit in a person's hand. The cube itself was said to have been crafted from the remains of a notable Buddhist Monk who went by the name of Genshin and despite the striking appearance of the cube, it is typically wrapped up in talismans when it is not being used, similar to Sukuna's fingers.
The Prison Realm is activated when the wielder of the cube says 'gate open'. This causes the cube to expand, with four of its corners shooting outwards to display a thin, fleshy red mass that contains a massive eye in the middle of it. To use the Realm on a specific target, as it was used on Gojo, it must be placed within four meters of them, and once this happens successfully, the cursed object then latches onto the target, negating all cursed energy and techniques to trap that target within itself. This was seen as it seemed to bypass Gojo's Infinity technique.
Once the wielder says 'gate close', the Prison Realm shuts, blocking the target from the outside world. Inside the Prison Realm, the target is essentially outside of time itself, as it does not pass inside the space of the cursed object. Due to this, the person inside does not age, nor can they die of starvation or thirst. During his imprisonment, Gojo described his time inside the Prison Realm like 'when work is insanely busy' and that it went by in a flash, despite being trapped for almost a month.
The Prison Realm, despite its amazing power, can only contain one person at a time though, and can only be used again if the person inside is freed or decides to take their own life. Because of this, Gojo was trapped inside the Realm and was absent for the entirety of the Shibuya Incident which numbered a total of 19 days within the manga, but took 3 years in real time serialization to show his return into the story.
While Gojo is subject to the rules of Jujutsu and Cursed Energy, the mechanism by which the Prison Realm affects him differs significantly from its impact on others, owing to his exceptional strength. Typically, uttering the 'gate open' incantation requires just a moment to seal an individual inside the Prison Realm. However, Pseudo-Geto recognized that this conventional approach would be too sluggish for Gojo, given his heightened perception with the Six Eyes technique. To overcome this challenge, Pseudo-Geto devised a cunning plan to effectively imprison the formidable sorcerer.
Initiating the Shibuya Incident, a veil was cast over Shibuya, granting exclusive entry to Gojo. Consequently, Gojo stood as the sole sorcerer within Shibuya during that time. As the events unfolded, Gojo descended to the train station, confronting Disaster Curses and numerous transfigured humans. Despite their formidable numbers, Gojo's overwhelming strength proved insurmountable. Intriguingly, the primary objective was not to eliminate Gojo but to execute a different plan altogether.
In response to the widespread chaos caused by the countless transfigured humans, Gojo activated his Domain Expansion for a mere 0.2 seconds. This brief yet potent activation served to completely immobilize and freeze everyone in the vicinity, allowing Gojo to swiftly navigate through all the floors of the station. In a matter of seconds, he systematically eliminated every transfigured human, accomplishing the task at hand. However, the immense exertion left Gojo thoroughly drained.
Seizing the opportune moment, Pseudo-Geto emerged from the shadows, capitalizing on Gojo's depleted state. Placing the Prison Realm strategically in front of the fatigued sorcerer, Pseudo-Geto aimed to ensnare him. Although Gojo still possessed the capacity to escape, Pseudo-Geto introduced a psychological element into the confrontation. Assuming the form of Gojo's closest friend, Suguru Geto, and employing his familiar voice, Pseudo-Geto played a mind game on Gojo. This unexpected and emotionally charged encounter left Gojo in a state of shock and disbelief, providing the opening needed for the Prison Realm to capture him. Even after the imprisonment, the Prison Realm required additional time to process Gojo's formidable presence.
How to Escape the Prison Realm
Ordinarily, the sole individual capable of liberating the trapped soul within the Prison Realm is the possessor of the cursed object, in this case, Pseudo-Geto. However, recognizing Gojo as the primary obstacle to his plans, Pseudo-Geto opted for a drastic measure. He hurled the Prison Realm down an 8000-meter trench, anticipating that the intense pressure at such depths would potentially prove fatal for Gojo should he manage to escape. Beyond the initial sealing method, two alternative means of freeing someone from the Prison Realm are known.
The first method involves accessing the Prison Realm through its 'back end.' The front end, which entrapped Gojo, was under Pseudo-Geto's control, while the back end was in the possession of Master Tengen during the Culling Game. Despite efforts to secure it from falling into the wrong hands, the back end's seal could be undone by cursed tools capable of negating Cursed Techniques, such as Toji's Inverted Spear of Heaven or Miguel's Black Rope.
In the absence of such tools, Master Tengen informed the heroes about the whereabouts of a character named Angel, possessing a cursed technique called Jacob's Ladder. This technique had the unique ability to nullify all Cursed Techniques within its range. The heroes located Angel and utilized her technique, successfully releasing Gojo from the Prison Realm during the Culling Game arc.
Jujutsu Kaisen can be read on Manga Monster for fun series.