This was a good read from start to finish. Unfortunately the author seems to have rushed it a bit with the folkloric explanations, unlike the Kyogokudou manga adaptations which always went into so much detail into the Japanese occult. The manga also kind of played the red herring game with Hotaru and Kaga's roles a bit too much, and the MC's friends ended up having no real connection the overarching plot.
Well, at least our MC got himself an immortal girlfriend.