Byoma means disease demons or disease. They are able to enter a person's heart and control them. People face anxiety, doubts and worries throughout their life. When there mentality cannot withstand the pressure byoma take over the person. There are many different types of byoma; transfiguring, influencing, and combined. They come in different forms and usually go undetected by people.
The longer a byoma remains atteched to a person the stronger it becomes by sucking the life energy. If it remains to long without being taken care of the person could lose their soul. When inside a persons body byoma have access to their memories.