"Kazuna is a young man with a fairly normal life. He attends high school, lives with his surrogate family, and models for his somber love-interest Yaegashi's paintings. But recently, he has suffered several crippling attacks at the sight of blood -- attacks which leave him incapacitated and out of control. Kazuna must now reunite with his sister who he has not seen in years, and discover the truth behind his family name and vampiric genes, before his bloodthirsty desires destroy himself, or others close to him."
Source: http://www.anime-planet.com/anirec/471.html // CHAPTER TWO