Vampire Akiba!!

Mitsuhiro Saionji lives with Makoto Akiba, the daughter of the best friend of his father, Munenori, a dubious novelist. The old man took over Makoto when she lost her life. Mitsuhiro, who was staking out a park to accompany his father's vampire search, witnesses Makoto wearing an unfamiliar coat and trying to suck human blood.