I think I read this about 13-15 years ago, around 2002-2005, having learned of it online. The protagonist was male, I think of Japanese descent. He was always on the move, either breaking into a building to sleep, or picking up a girl at a bar to have a place to sleep. The book opened with him slipping out on his latest conquest. I think he meets a girl and then she disappears, and later that night, he's attacked by a floating head that comes through his window (that time, I think he was slumming in a building he'd broken into, maybe a laundromat?). I want to say the floating head is explicitly noted as a rokurokubi, the Japanese spirit. He pound it to the ground by impaling it through the ear with his knife, and interrogates it, confirming that he was its target. I think the daylight kills it.
In the end, he winds up in some sort of reality-warping fight with the villain, something which I want to say involved a clay amulet or necklace, which is broken by the end of the conflict, with the very end confirming that he still has powers.
The book was in English, and I think I got it from the library in Newark, OH where I was living at the time. I remember the cover being dark, maybe black, with at most minimalist cover art. I keep wanting to say that black arrows had something to do with the title, but that detail is hazy. There may have been a sequel, but if so, I don't remember any details about it.