Jormungandr is a strategic-class militarized spirit sealed in the postwar period in Mine Town Gado.
Because of its tremendous strength, it was impossible for an individual to control it. In the end, it could only be controlled by ritual Kagura performed by several hundreds of elementalists. It was surely a weapon of mass destruction.
Jio Inzagi, with the help of Restia, tried to unseal Jormungandr but Kazehaya Kamito, Fianna Ray Ordesia, Rinslet Laurenfrost, and Ellis Fahrengart stopped them.