Anime

One hundred mamodo (known as "mamono/demons" in the original version) go to Earth every 1,000 years to battle to be the king of the mamodo world (referred to as makai in the original, which can be translated as hell). Each mamodo has a particular element which it can control and attack with, a set of body supporting spells, and other spells (e.g. a defensive spell), all via the use of a special spell book. Each mamodo needs a human partner in order to use his or her spell book, and if his or her spell book is burned, the mamodo is forced to return to the mamodo world. While the spells in each book typically are different for each mamodo, there are mamodo that share spells. The human and their mamodo gain these spells through experience. Each spell book is a different color. The last mamodo standing without their book burnt is the new mamodo king.