Hildisvíni (ヒルディスヴィーニ Hirudisuvuīni?) is a boar in Norse mythology that is said to be used by Freyja for riding. In the world of Toaru Majutsu no Index it is one of the creatures summoned through the spiritual item Brísingamen by Freyja, a GREMLIN magician. It appears in the GREMLIN invasion of Tokyo, and was summoned by her to do battle against Kamijou Touma.