The most significant plot twist of "Jujutsu Kaisen 0" is the revelation about the origin of Rika's curse. Throughout the film, both Yuta and the audience are led to believe that Rika's spirit cursed Yuta after her death. However, the climax reveals the opposite to be true: Yuta inadvertently cursed Rika. Overwhelmed by grief and rejecting her death, Yuta's immense latent cursed energy bound her soul to him, transforming her into the vengeful spirit. This recontextualizes the entire narrative as Yuta's struggle with his own guilt and power, not as the victim of a haunting. Gojo confirms that Yuta is a distant descendant of one of Japan's most powerful sorcerers, which explains his vast reserves of cursed energy.
The film's ending sees Yuta making a pact to give his life to Rika in exchange for her full power to defeat Geto. This act of selfless love paradoxically breaks the curse. By fully accepting their bond and being willing to join her in death, he fulfills their childhood promise, which allows Rika's soul to be freed. She appears in her original human form, thanks him for the years they had together, and peacefully passes on. In the immediate aftermath, a grievously wounded Suguru Geto is confronted by Satoru Gojo. After a brief, unheard exchange that implies the remnants of their old friendship, Gojo executes him off-screen. The post-credits scene is crucial for the main series: it shows Yuta training in Africa with Miguel (one of Geto's former allies), where they are met by Gojo. This scene confirms Yuta is alive and well, has kept his cursed energy, and is actively working with Gojo, setting the stage for his re-entry into the story after the events of the anime's Shibuya Incident arc.