Sacred†Vampire-セイクリッドヴァンパイア-

Kiryuu Kazuma is one of the last representatives of an endangered breed: Vampire. In a world guided by teachings of the Roman Catholic Church, the organization that brought his species to near extinction, Kazuma condemns the existence of God. It is an irony that does not escape him, upon discovering he has fallen in love with a woman who seeks to devote her entire life to the Lord. To win her heart, Kazuma must conceal his predatory past and inhuman nature, for if she ever learned the truth of his origin, a Child of God would never accept a Spawn of Satan.

[From Eroge Review]