Yaogai

Yaogai (精霊 (妖怪), Yāoguài; Pinyin for "Monsters", Japanese for "Nature Spirits") is a result of merging human soul and an animal spirit in order to produce a hybrid which personifies the force of nature itself. Yaogai inhabit one of the Six Spirit Realms. Tiryag-yoni - the Animal Realm. When exposed to the Spirit Modification Technique a Yaogai can seal its animal form and powers in a form of a weapon, thus becoming an Ayakashi.

Overview
Yaogai is a soul created by merging a human soul and an animal soul together in order to create a unity between a man and nature. When a soul gains a sufficient amount of Reiryoku it can merge with another one; if it's a powerful animal soul it can posses a human and when it's a powerful human, they can absorb the animal. Depending on which soul initiates the transformation, Yaogai will look like a human with animal features or as an anthropomorphic beast.

Powers & Abilities
Longevity: As a supernatural spiritual beings, Yaogai can maintain their youthful appearance and physical prime for centuries. Sometimes, a Yaogai can willingly pose as an elder person in order to conserve their energy.

Yaoki (妖気, Demon Energy; lit. "Magic Energy"): Type of energy created by fusing Reiryoku from a human and Shiryoku, Natural Energy, harvested from plants, animals and the elements. When this two are merged, a unique type of energy is made. Y&#333;ki is used by Yaogai to cast spells, protect themselves from enemies and support their existence. It is used by both Yaogai and the Ayakashi.
 * Yaoshu (妖術, Monster Arts; lit. "Sorcery"): The art of manipulating Yaoki energy to produce variety of effects. It allows Yaogai and Ayakashi to produce barriers, seals and a large range of offensive magic. Some species of Yaogai (such as Yasha) are naturally gifted in the magic arts of Yaoshu.