Seith Magic (セイズ魔法 Seizu Mahō) is a Caster-Type Magic.
Seith Magic is a type of Magic that deals directly with trapping wandering souls and manipulating them. So far, there are only two known variations of Seith Magic: Human Possession, which deals with trapping wandering souls inside objects and manipulating them, and Animal Possession, which deals with trapping animal souls inside the user's body to use whenever they wish. Bickslow utilizes Human Possession to trap souls into dolls and use them for various purposes, such as attacking, defending, and transportation. Nab Lasaro utilizes Animal Possession in order to engage in hand to hand combat with others.
- In real life, Seiðr (which is sometimes anglicized as seidhr, seidh, seidr, seithr, or seith) is an Old Norse term for a type of sorcery which was practised in Norse society during the Late Scandinavian Iron Age.