Elemental

Spirits (精霊), like Demons and Angels, are supernatural life-forms that reside in the spiritual world. They come into being from natural energy or as offshoots of a grand spirit. As with demons, lesser spirits typically hold no ego, and is a trait reserved for only greater spirits -- even then, only an exceptional few at that.

Spirits only associate themselves with the five natural elements of Earth, Sky, Wind, Water and Fire. There are spirits of Light as well, and being liked by one is a sign that the individual has the qualifications to be a hero.

Just like most spiritual beings, spirits can interact with the physical world through a vessel. They hold a racial advantage to demons but are inferior against angels.

Trivia

 * Despite having a racial advantage to demons, they have yet to win a single fight against demons in the series. In fact, all spirit VS demon battles ended in the spirit's instant defeat, because they were matched against ridiculously strong Primordial demons.
 * Greater spirits have their own name as subspecies:
 * Fire: Ifrit
 * Water: Undine
 * Wind: Sylphide
 * Earth: War Gnome