Rustblaster (ラストブラスター) is a 1 volume manga by Yana Toboso, started in 2006.
Plot: In the Vampire Mercenary Specialized School, "1000 Years Academy," the most unvampire-like vampire at the academy, Aldred Van Envurio, and the human transfer student, Kei Yosugara, meet by chance. But what they didn't know was that it was a fate the world depended on.