It starts with one of those classic "you wake up confused and bound in an empty room" openings, but things quickly go haywire from there. As you eventually find out, your job is (Spoiler - click to show)containing demons for a temple by serving as their human vessel. All you have to do is let yourself be bound, then sleep in peace. Easy, right? But something's set the temple on fire, and the voices in your head are getting louder...
The game makes good use of its situation - at the start your past is uncertain, your identity is in flux, and there's multiple confusing voices in your head telling you what they think you should do. But as you play, you realize what your situation is and that makes the "right" choices more clear. In other words, this is one of those games that benefits hugely from repeat playthroughs. I played it four times and got, I think, all the endings. I think I can safely say (Spoiler - click to show)the voices in your head are supposed to be some degree of ambiguously evil. After I realized this I stopped murdering people, though to my disappointment it didn't seem to impact the endings at all.
(Spoiler - click to show)Demonic possession is kind of overplayed, and there are slightly unfortunate implications with the whole "people who hear voices are psychotic murderers" thing, but I'm personally fond of "voice in your head" narratives, and it did work well with the song.
Took me maybe ten minutes to get all the endings (lots of repeat text between the different paths). Having more story differences between the paths, or more elaboration on the world in general/what exactly are the voices in your head? could make the game feel more substantial. It was fun nonetheless.