In 2086, Naunax, an extraterrestrial mothership carrying 50 thousand life-forms calling themselves Simurians, appears above Earth. Simurians possess powers similar to those of Japan's jujutsu sorcerers, and thus all diplomatic negotiations are redirected to the Japanese, who are tasked with assessing whether coexistence is possible.

Though facing a special grade incident rivaling Sukuna Ryoumen's attack 68 years prior, humanity welcomes the aliens—for now. Fearing that these powerful beings could declare war, Japan agrees for a Simurian envoy to accompany jujutsu sorcerers to school and missions. Two teenage sorcerers—Yuuka and Tsurugi Okkotsu, siblings and grandchildren of the late Yuuta Okkotsu and Maki Zenin—are chosen to team up with Marulu "Maru" Val Vol Yelvori, a friendly, three-eyed Simurian. As both sides withhold crucial details yet want eventual harmony, it falls to Yuuka, Tsurugi, and Maru to maintain the fragile peace and prevent mutual ruin.