I have been wanting to play this ever since I found it. I'm sorry I didn't get to finish to review this before the end of the jam. But here goes:
I wanted to say, I really like the art. Particularly the CGs. They sell the story a lot! The sprite art is also pretty cool, but I wished they looked a tad bit more androgynous, like the CGs version. They still read as the same characters, though. Much like how it would be a manga version from the anime version.
I'd have to say my only qualm with the CGs is that they are too dark. Even if I know that was the intention it reads as unclear.
As for everything else, this obviously is in dire need of music. Not only because generally you need it for certain scenes, but this is literally a music-themed story. In this case, it's kind of a big deal. Plus, it's not just the music - it's the sound design in general. You need a static sound every time there's static for sure.
The concept of the story I do like a lot. The reason I was really looking forwards to this was especially because of the summary. Now the game writing itself, I do think it could use with a few tweaks. The twist becomes way too obvious way too fast. And the fact that the protagonist isn't aware that the friend is being a total ahole to him reads as unlikely because the guy isn't even trying to be subtle. Maybe you were anxious about making it to the scary part for the jam and felt you needed to rush things and that's why?
But before this reads wrongly, I think this is a solid 8/10. I don't mean to discourage you at all, I think think has a lot of potential. It just need a bit of tweaking, that's all