Yuji Itadori is a high school student with unnatural physical strength and athletic ability. One day, at school, his friends attract Curses by unsealing a rotten finger talisman. Yuji swallows the finger to protect Jujutsu Sorcerer student Megumi Fushiguro, tasked with retrieving the finger, unwittingly becoming host to the powerful ancient sorcerer Ryomen Sukuna. The leaders of the Jujutsu Society intend to exorcise Sukuna, and Yuji, by extension. However, noticing Yuji's capability to retain control over his body, Satoru Gojo, the strongest sorcerer in the modern Jujutsu world—brings him to the Tokyo Prefectural Jujutsu High School for training. Gojo has Yuji's execution postponed until he consumes all twenty of Sukuna's fingers, thereby enabling Sukuna's complete destruction through his death.
Meanwhile, a group of intelligent Cursed Spirits plot an elaborate attack to reform Jujutsu according to their ideals. The group is led by Suguru Geto, a mysterious sorcerer and Curse User believed to have been killed by Gojo a year earlier, whose entourage includes the soul-manipulating Curse, Mahito; the fire Curse, Jogo; and the nature Curse, Hanami. Yuji is devastated after Mahito kills his friend Junpei Yoshino, but is unable to take revenge. Mahito infiltrates Tokyo Jujutsu High and steals three "Death Paintings"—dormant, half-human, half-Curses—before summoning them to their full form. During a battle, two of them end up being exorcised, leaving Choso as the sole Death Painting survivor.
On Halloween night in Shibuya, Gojo destroys Hanami, but is ultimately sealed by Geto, revealed to be the ancient sorcerer, Kenjaku, inhabiting Geto's corpse. Choso defeats Yuji, but spares his life after having a vision that reveals they are brothers. Subsequently, Jogo force-feeds an unconscious Yuji ten Sukuna fingers, enabling Sukuna to briefly take control. Sukuna kills Jogo and nearly destroys all of Shibuya in the process. He then hands control back to Yuji, who is overwhelmed by the sight. With help from Kyoto Jujutsu High student Aoi Todo, Yuji defeats Mahito, but Kenjaku absorbs the Curses and awakens countless sorcerers, advancing his millennia-old plan for a new era of Cursed Spirits.
In the aftermath, the Jujutsu higher-ups reinstate Yuji's immediate execution and appoint second-year student Yuta Okkotsu, who instead helps Yuji. They group together with other sorcerers to seek Master Tengen—an immortal, part-Curse, part-human sorcerer. Tengen reveals Kenjaku's plan to merge the former's consciousness with the entire Japanese population through the "Culling Games"—a battle royal among the awakened sorcerers, designed to accumulate vast amounts of Cursed Energy. Eventually, Tengen is captured by Kenjaku. Yuji and his allies rescue Megumi's stepsister, Tsumiki, from being forced into the Culling Games; however, she is killed by Sukuna after he takes control of Megumi's body.
A month later, the unsealed Gojo battles Sukuna, who fatally bisects him. Meanwhile, Yuta defeats Kenjaku, who, before dying, makes Sukuna the Culling Games' master. The remaining Jujutsu Sorcerers attempt to fight Sukuna, but are overpowered as he regains his true form. In a flashback, it is revealed that Sukuna ate his twin brother in the womb a thousand years ago. The twin's soul reincarnated into Yuji's lineage, and Kenjaku's possession of Yuji's mother during conception combined to forge his unique physique and his capacity to host Sukuna. With help from his allies, Yuji manages to defeat Sukuna, although Choso sacrifices himself in the process. Megumi successfully frees himself from Sukuna, who subsequently disintegrates. Some time after the battle, Yuji reflects on Gojo's hopes and trust in him, and although Sukuna's last finger is shown, his defeat makes his return unlikely.
