"Jujutsu Kaisen 0" serves as a prequel to the main "Jujutsu Kaisen" series, centering on Yuta Okkotsu, a high school student haunted by the cursed spirit of his childhood friend, Rika Orimoto. After a tragic accident, Rika's spirit becomes a powerful and uncontrollable curse bound to Yuta, causing him immense emotional distress and danger to those around him. Satoru Gojo, a prominent jujutsu sorcerer, intervenes and enrolls Yuta at Tokyo Jujutsu High, a school dedicated to training individuals to combat curses.

At the school, Yuta meets fellow students Maki Zenin, Toge Inumaki, and Panda, who help him navigate his new life as a jujutsu sorcerer. Under Gojo's guidance, Yuta begins to learn how to control his cursed energy and harness Rika's immense power. The narrative explores Yuta's internal struggle with guilt and fear, as he grapples with the responsibility of wielding such a dangerous curse.

The central conflict arises when Suguru Geto, a rogue jujutsu sorcerer, plans to unleash a wave of chaos by using cursed spirits to eliminate non-sorcerers. Geto targets Yuta, seeking to exploit Rika's power for his own agenda. Yuta is forced to confront his fears and insecurities, ultimately deciding to fight to protect his friends and the world from Geto's destructive plans. The climax features a high-stakes battle where Yuta fully embraces his abilities, demonstrating growth and resolve.

The story concludes with Yuta gaining control over Rika's curse, transforming her into a protective force rather than a destructive one. This resolution marks a turning point in Yuta's journey, as he solidifies his role as a jujutsu sorcerer and prepares to face future challenges. The film ties into the broader "Jujutsu Kaisen" narrative, providing context for Yuta's role in the main series while exploring themes of loss, redemption, and the burden of power.