He's My Only Vampire

He's My Only Vampire (純血+彼氏, Junketsu + Kareshi) is a shojo manga by Aya Shouoto. It ran in the manga anthology Aria from July 2010 to September 2014, and is complete with ten volumes total. Yen Press released it in English.

Plot
Kana Takachiho used to be good at sports until she was injured in a freak accident, which loses her the scholarship keeping her and school and earns her the disdain of her fellow classmates. Furthermore, her childhood friend, Aki, is a vampire! He drinks her blood and turns her into his “thrall". Now, Kana is thrust into a dangerous game to find demonic powers known as "STIGMA".