The double message in the beginning of the description was really clever and unique. I would cut out the rest of the description as this part alone gives the reader enough information. The double meaning is intriguing enough to get people reading your foreword.

I'm going to assume that the foreword is a kind of background to the rest of the story. It's a really good idea as it provides that information without bogging you down in the actual story. On another note I did notice a few minor punctuation mistakes. “God, let Guissepe” doesn’t need the comma as it makes it sound stilted, so does “naming it, the”. Other than that the foreword captures my interest and makes me want to the rest of the story.

I’m assuming that the girl L.joe meets in the creepy room is the devil. If so her gestures are off putting e.g. she sighed and slapped her forehead or she smirked and flicked his forehead. These gestures come off as kind of cutesy for the devil, if you know what I mean. I’d expect him/her to be cold, not engaging in physical contact or slapping him/herself in the head. It was just something odd for me personally and detracts from the believability of the character.

Also I’m a little confused with Ahn Cheonsa. Does L.joe know her or not? I’m going to assume she’s the girl he met in the creepy room. It wasn’t clear whether l.joe was confused by her presence or just interested in her or whether she was familiar to him, which is something you will probably want to clarify if you don’t want to confuse people.

That aside I really like where you’re going with your characters and I see some potential for great development.

I’ve only read the first three chapters so I don’t know what else is going to happen but I really like where it’s going so far. It seems to be well developed at this pointand I like the link between the foreword and the rest of the story. The only complaint I have is that it’s a little rushed, it’s difficult to contain yourself when you get an awesome idea like this but taking some time to develop things is definitely worth it. A rushed or “jumpy” story can sometimes be hard to read and has the potential to leave readers in a head spin with the amount of information you're bombarding them with. I’m looking forward to seeing what else comes out of this plot.

Overall it is well structured however there are a few minor things. In the first part it where it says “school ended an hour a go and there was probably no one left in the highschool” could be left at 'no one left', it sounds odd if you get a repetition of words and we get that he’s in a school without being told twice.

The second paragraph has an over use of the word ‘he’, try to find some other way to start the sentence so you avoid getting repetitive. I would also ‘show’ rather than ‘tell’ that there is something off about the music room e.g. “with an uneasy fumble for the switch the room was illuminated in cold fluorescent light”. With fantasy/supernatural fics you can be more descriptive and it definitely pays off as it makes it easier for readers to engage and imagine what’s going on rather than being told straight out what’s happening.

Sentences like “placed the papers on a stand before he walked back to the piano to get the violin and walk back” sound tiresome, cut out the “and walk back” and maybe change the “get” to “retrieve” as the reader will assume he walks back to the stand, find ways to be descriptive but not repetitive. With a little tweaking this fic is going to be awesome.