Necromancy

A girl is cursed with something that makes her pass out easily due to blood loss in the form of coughing. One day, she decides to run away from the life she had been living but is cut short by a fist to the ribs. When she wakes up from her coughing hysteria, she finds herself in a land of mysterious beings that can't be seen by the human eye. A man wearing a Black Death doctor's mask nurses her back to health and says he can cure her unknown disease but on one condition- She must become a necromancer like him and be his assistant for as long as he lives.