Decades after the original Jujutsu Kaisen story, an alien species called the Simurians arrives on Earth wielding power that looks a lot like cursed technique, and Japan's jujutsu community is handed the job of keeping the peace. Sorcerer siblings Yuuka and Tsurugi Okkotsu, grandchildren of Maki Zenin and Yuta Okkotsu, are partnered with Marulu, a Simurian envoy sent to test whether the two species can coexist. As missions pile up, both sides keep as many secrets as they share.