WARNING: The following contains spoilers for Episode 18 of Jujutsu Kaisen, "Sage," now streaming on Crunchyroll.
As Jujutsu Kaisen's Cursed Spirits lay siege to Jujutsu Tech during the Exchange Event in Episode 18, two characters need to be especially careful: Itadori and Gojou. They've been targeted before by Suguru Getou and Mahito's team of Curses and are continued threats to the Cursed Spirits' plans.
Though Itadori finds himself in their crosshairs because they hope Sukuna will gain control of his body and join their cause, Gojou is singled out simply due to how dangerous he is. As by far the strongest Jujutsu Sorcerer, Gojou poses the biggest threat to stopping the Cursed Spirits from attaining their goal of eradicating humans. However, instead of defeating Gojou, they intend to capture him with something called the Prison Realm.
Jujutsu Kaisen's Exchange Event Is Interrupted By Cursed Spirits
The excitement of Jujutsu Kaisen's tournament arc, which pits the students of Jujutsu Tech's Tokyo and Kyoto branches against one another, is interrupted by a much more sinister threat. While the Kyoto school principal -- Yoshinobu Gakuganji -- discreetly added a dangerous Curse to the battlefield to help his students kill Itadori, his schemes were snuffed out by the Cursed Spirits infiltrating Jujutsu Tech.
Cursed Speech user Inumaki is the first to encounter Hanami -- a mysteriously powerful special-grade Curse -- before he is chased and meets with Fushiguro and Noritoshi Kamo. Though the fight between Fushiguro and Kamo, who uses a Blood Manipulation Cursed Technique, has tense moments, the two quickly put their differences aside to focus on their mutual enemy. Unfortunately, everyone is spread to various corners of the school, and the Cursed Spirits make explicit attempts to interrupt communication -- smashing Fushiguro's phone to stop him from contacting Gojou.
Satoru Gojou Remains Targeted
After an attack on the school is confirmed, Gojou -- along with the other Jujutsu Tech administrators -- notice the veil placed around the surrounding area. This particular veil is especially powerful, but it's only meant to keep one person out: Gojou Satoru. Everyone else can pass freely through its walls, confirming to Gojou that he is a target.
During Jougo's clash with Gojou, he quickly learned that he was no match for the impressive sorcerer's Limitless Cursed Technique. As Getou had warned him, the only way to deal with Gojou is to trap him within a special-grade cursed object known as the Prison Realm. Getou and the Cursed Spirits have been plotting to infiltrate Jujutsu Tech since before the Exchange Event began with the intention of stealing all of Sukuna's fingers in the school's possession along with the Prison Realm.
Jujutsu Kaisen Confirms a Traitor -- But Doesn't Reveal Them
As Gojou accesses the veil's quality around the school, he notes that there must be a skilled Curse user among their enemies. However, the more critical piece of information Gojou realizes is that the Cursed Spirits would need a degree of intel on Jujutsu Tech to slip past Tengen's protective barrier around the school and create a veil that specifically keeps him out.
At the beginning of the Exchange Event, Gojou discussed the possibility of a traitor working with the Curses with fellow teacher Utahime Iori. While this surprise attack confirms his suspicion, it still begs the question of who that traitor is. Another variable in the situation is Getou, who actively avoids being seen by anyone other than the Cursed Spirits and has previous ties with Jujutsu Tech.
Regardless, Mahito and Getou have made it abundantly clear that Itadori and Gojou are high valued targets who have significant roles to play if their nefarious plan to eliminate humans is to succeed. If they find a way to force Itadori to surrender his body to Sukuna and give the King of Curses the gift of half a dozen fingers, the situation drastically shifts in the Curses' favor. Worse yet, if they successfully trap Gojou in the Prison Realm, then it becomes dangerously bleak for all of the Jujutsu Sorcerers.