Angel Dust

Angel Dust is a hentai manga by Kouta Hirano.

Summary
Anderson, a mafia assassin tries to escape from the police after being betrayed and backstabbed by the organization he works with (taking along with him 50 kilograms of heroin). To trick his pursuers, he dresses up as a priest and hides himself in a village. A nun named Kris, offers him work at the church and he accepts, seeing this as an opportunity to live the rest of his life atoning for his sins. But one day Flanders, a mafia member (and an ex-partner of Anderson) finds the church he works at and, while Anderson is absent, he and his partners repeatedly rape Kris. They demand the return of the stolen heroin and threaten to kill Kris. But Anderson proves too skilled for them to handle and he defeats them. Kris and Anderson now flee from the organization and its leader, the ghost of a Nazi.

The character of Anderson obviously influenced the character of Alexander Anderson in the Hellsing series, several of the characters from Kohta Kirano previous hentai projects made it into the Hellsing series.