Vs. Mahito Arc

The Vs. Mahito Arc is the fourth story arc in Gege Akutami's Jujutsu Kaisen series.

The Death by Disfiguration Investigation
Junpei Yoshino, a student from Satozakuro High School, witnesses the uncanny demise of his fellow classmates. They're gruesomely mutated by the hands of the special grade cursed spirit, Mahito in one of the Kinema Cinema theaters. Rather than being fearful, Junpei follows Mahito out of the theater and makes his acquaintance. At the same time, having finished his training with Gojo sensei, Yuji is assigned to help Grade 1 sorcerer, Kento Nanami. They arrive on the scene together to investigate the murders at Kinema Cinema.

The culprit is already gone, but they investigate the premises to find two strange curses lurking on the roof. Yuji is eager to prove the fruits of his labor but Nanami wants the young man not to go overboard. He doesn't recognize Yuji as a full-blown sorcerer and views him as a child. Yuji uses his newly developed Divergent Fist and Nanami uses his Ratio Technique to easily dispatch the curses. Nanami takes a photo to confirm his suspicions before bringing the corpses back to Doctor Shoko. She discovers that these aren't curses, instead, they're ex-humans who were mutated by cursed energy.

Inside Mahito's lair, the curse appears to have taken a liking to Junpei and explains the nature of his existence. Mahito feels that he was born from the hate within people and taps into the dark side of Junpei's mind. Junpei has always felt indifferent toward people because he doesn't think humans have hearts. Mahito encourages him not to stop at indifference and claims to support everything Junpei feels.

Sometime later, the investigation continues above ground with Yuji, Nanami, and Ijichi overlooking the clues left behind by the murders. Yuji wants to move in, but Nanami tells him to meet with and possibly interrogate Junpei Yoshino, the only known witness. Yuji moves out on his own, believing that Nanami is looking closer into their clues. However, Mahito left behind residuals of his cursed energy as an open invitation to the jujutsu sorcerers. Rather than putting Yuji in harm's way, Nanami infiltrates Mahito's lair alone.

Underground Clash! Nanami VS Mahito
Nanami easily dispatches the ex-humans turned curses Mahito has guarding his territory. They fight using their cursed techniques and Nanami manages to break Mahito's guard. Mahito reveals that his ability allows him to re-shape souls, including his own. This makes Mahito capable of healing himself as well as transfiguring others. Rendering Nanami's assaults useless, Mahito takes the upper hand in the bout and injures Nanami by touching his soul.

While Nanami struggles underground, Yuji and Ijichi track down Junpei skipping school. He's caught by his teacher, Sotomura, and Ijichi plans to use a fly-head curse to test Junpei's awareness. Sotomura complicates the situation and Yuji awkwardly interrupts them to stop the fly-head. In order to get one on one with Junpei, Yuji gets rid of Sotomura, claiming that he felt Junpei disliked him anyway.

As Nanami enters overtime, Mahito notices his opponents cursed energy beginning to swell. the Grade 1 sorcerer quickly turns the tables on Mahito using his Ratio Technique: Collapse, to completely implode the area around them, crushing Mahito. Nanami knows this won't be enough to kill his opponent and says they'll meet again before escaping.

The Fall of Junpei's Heart
Yuji manages to talk with Junpei at his school and despite their clashing personalities, they manage to bond over movies. They're found by Junpei's mother, Nagi Yoshino, who invites Yuji to dinner. He accepts and eats at the Yoshino house, managing to get along very well with Junpei and his mom. At the same time, Mahito escapes his prison of debris and Nanami dresses his wounds back at his home. While Mahito is excited by the prospect of fighting Nanami again, the jujutsu sorcerer is worried Mahito will grow too strong for jujutsu sorcerers to handle.

That night, Junpei asks Yuji if he's prepared to kill as a jujutsu sorcerer. Yuji admits that he knows the choice will present itself but wants to believe that he won't devalue human life. After Yuji leaves, Nagi finds one of Sukuna's Finger on the table, attracting curses that murder her. Those close to Junpei learn of his mother's death, including Mahito and Yuji.

Mahito influences Junpei to get revenge. He gets Junpei to target his anger at an old classmate named Shota Ito who burned Junpei's face while bullying him. Shota is being recognized at a ceremony at Satozakuro High. Junpei interrupts the event, knocking out everyone in the gym and attacking Shota with the cursed techniques he learned from Mahito. Outside, Mahito and Suguru Geto plan to use Junpei to draw out Yuji and Sukuna.

Yuji learns about the commotion at the high school and goes alone despite Ijichi's misgivings. Yuji finds Junpei assaulting Shota and stops him. Junpei tells him to stay out of the way and attacks him with Moon Dregs, a giant jellyfish-like shikigami. Yuji fights them back while trying to get through to Junpei, begging him not to throw his life away. Junpei tells Yuji to stop acting compassionately because it's all lies and people don't have hearts.

Yuji feels that Junpei's words are an empty attempt to hide his pain and overpowers by attacking Junpei rather than the shikigami. Junpei can't believe that people have hearts, because someone cursed his mother. He breaks down into tears and uses his shikigami to attack again. This time, Yuji allows himself to be pierced in order to get through to Junpei. Yuji promises to help Junpei find out who killed his mom if the latter will join Jujutsu High. Just as Yuji reaches Junpei's heart, Mahito arrives.

Mahito pins down Yuji and the latter realizes that this is the man Nanami fought. Junpei tries to tell Yuji to stand down and then realizes that Mahito has been an evil person all this time. Just as he puts the pieces together about his mother's murder, Junpei is mutated by Mahito. Mahito forces Junpei to fight Yuji, trying to force the human boy to rely on Sukuna. However, Sukuna refuses to heal Junpei and both curses laugh at Yuji's expense.

Junpei dies and Yuji realizes that he has no choice but to accept the truth. Mahito and Sukuna are nothing but curses. Yuji taps into his hatred and strikes Mahito. Initially, Mahito believes this attack to be useless but then he starts bleeding. Mahito surmises that Yuji can perceive souls thanks to sharing a body with Sukuna. Mahito hopes to draw out enough of Yuji's hate to force him to make a Binding Vow in Sukuna's favor by leaving him no other choice.

"I'm Gonna Kill You"
Filled with rage, Yuji tells Mahito that he's going to kill him. They clash all through the school but Mahito gains the upper-hand after piercing Yuji's body with spikes. He tries to finish Yuji off by touching his soul but Sukuna stops him, warning him to never try again. This gives Yuji an opening to assault Mahito, stating that he's going to kill Mahito.

Despite Yuji's advantage, Mahito gets behind him and nearly ends the fight. Before it's too late, Nanami suddenly arrives to back up Yuji. Rather than scolding him, Nanami creates a plan of attack after noticing that Yuji's attacks can actually hurt Mahito. Fighting together, they attack relentlessly to create openings for each other. In order to focus on killing Nanami, Mahito creates ex-humans for Yuji to fight. He pins down Nanami, believing that Yuji won't have the heart to kill. However, he's wrong and Yuji helps free Nanami.

Yuji and Nanami unleash an all-out assault that brings Mahito near death. This allows him to feel death's embrace and receive its inspiration. Staring his defeat in the eyes, Mahito goes beyond his limits and unleashes his very own Domain Expansion. He only brings Nanami inside and the Grade 1 sorcerer accepts his defeat, knowing he cannot possibly win inside a Domain. After recalling why he decided to rejoin Jujutsu High, Nanami accepts his fate and claims he has no regrets.

Before Nanami is slain, Yuji breaks into the Domain from the outside. This forces Mahito to touch Sukuna's soul once again, irritating him. Sukuna states that he already said there wouldn't be a second time and attacks Mahito's soul, gravely injuring him. With that, Mahito's Domain crumbles and the battle comes to an end.

Before they can finish Mahito off, he escapes by expanding his body as bait for Yuji to attack. While they're focused on the bait, Mahito escapes back underground through the sewers.

Yuji and Nanami return to base to dress their wounds. Nanami decides not to scold Yuji and thanks him instead for saving his life. Yuji is saddened by the fact he couldn't save Junpei or his mother and has doubts about helping people to a natural death. Mahito says Yuji shouldn't be so hard on himself and officially recognizes him as a Jujutsu Sorcerer.

While Mahito recovers underground, he swears to get revenge by killing Yuji's spirit. He's confident that the age of curses as the dominant species will come as long as a force like Sukuna exists. Still plagued by the lurking hatred for Mahito, Yuji swears never to lose again until he destroys Junpei's killer.

Characters Introduced

 * Kento Nanami
 * Junpei Yoshino
 * Nagi Yoshino
 * Sotomura
 * Shota Ito
 * Takuma Ino

Setting
September 2018 - Kawasaki City, Kanagawa Prefecture:
 * Kinema Cinema: The movie theater where Mahito murders students from Satozakura High, leading to the investigation that sends Yuji and Nanami on his trail.
 * Mahito's Underground Lair: Mahito's territory in the sewers where he experiments on humans using his Cursed Technique. He allowed Junpei to talk and left a trail of his residuals to lead Nanami there to fight. Nanami ultimately collapsed most of the hideout using his Cursed Technique to finish his fight with Mahito.
 * Satozakura High School: Junpei's highschool. The site of the final clash between the Jujutsu Sorcerers and Mahito.