He is a vampire descendant. Instead of sucking blood, he uses blood transfusions. He is really anemic (and hungry) thus he walks around while the blood is being transfused (a portable blood transfusion). He can go up to 5 days without blood transfusion, that's his limit. One of his vampire powers is to repel ghosts. 

Over the years, the vampires have developed, so he can be out in the sunlight, eat garlic, carry crossed, though silver etc. His personality changes depending on which blood type he uses: A=studious, O=laid-back, B=lazy, AB=spacy. He prefers type O. He is very kind, considerate and light-minded.