Shiyuu’s are the name of the dark deity’s that are born from an intense amount of anger, rage or hate. Shiyuu’s are best known for their massive amounts of super natural power, ki and abilities when their host is in danger or need of assistance they will act and give them some of their power although some Shiyuu’s do it for the wellbeing of their host and some to keep themselves alive seeing as how if their host die they will die as well while the other’s would do it to ensure their host safety as some Shiyuu’s are not all bad and grow bonds with their host.
In order to gain control of a Shiyuu’s power the host must fight their Shiyuu in a 1 on 1 battle in order for their Shiyuu to make sure their host have enough mental and physical strength to hold their power alone, if a host fails to do so the Shiyuu will take over the host mentally and fight for them when in a pinch however if one doesn’t have enough will power some Shiyuu’s will personally take over the host’s body and make it their own.
If a host knows a summoning technique they can summon their Shiyuu and have them fight alongside them whenever needed. The amount of time the Shiyuu can stay out is judged by the bond or control the host has over their Shiyuu.
Shiyuu’s have many forms and shapes; some Shiyuu’s take the form of animals and humans. Even if a Shiyuu takes the form of a human their soul will have the persona of a demon transforming their host into the form of that demon if granted too much power.
The Shiyuu’s soul is the very essence of a Shiyuu’s being regardless in shape or form. Shiyuu’s Souls carry their ki and power and when they grant their host to much of that power it will transform them into the form of a demon which can come in the form of any creature: mammal or super natural beings.
The spirit is what the Shiyuu represents. For example Andre’s Shiyuu, Amaterasu, is known as the fox spirit and at times the spirit can affect the host as well. If Andre were to get affected by too much of Amaterasu power her ki will attach to his skin covering up his entire body turning it into the form of a fox as well as sprouting him pointy like ears, a tail(s) (depending on how much power is leaked) and little pricks of fur that can be noticeably be seen on the body he will also lose his sense of humanity.
A Shiyuu can only be removed if the host gets his or her Soul purified.