The story takes place takes place based off of historical Japan, so music that fits that era would be preferred. I'm a huge fan of the Vocaloid/music composer, -MASA Works DESIGN-, if you want to look him up for some reference (I mainly mean his onibi and sister series such as The Fox Wedding, The Secret Box, and Shikyou the Amanojaku - the original not the versions for the ADULT album).

However, typical horror RPG music would also work very well!