Hanna is Not a Boy's Name Volume 1

Hanna Falk Cross is a paranormal investigator. Or at least, that's what his card says. But as people get to know him, one finds that there is not a lot of detective work in Hanna's daily life, but rather more of a mad scramble to get out of whatever mess he so wonderfully landed himself (and others) in.

Having previously worked solo, Hanna now finds himself with a new partner; a man dead for at least a decade with no memory of his life and no desire to unearth it. Shockingly, the dead man has more sense in him than Hanna ever did and begins to dutifully keep track of all of their cases together, all while trying to guide the over-eager boy gently through every day without getting himself killed.

It should be easy enough, but seeing as the man is dead in the first place, he can't vouch for how good he is at staying alive.