This series is a solid 9 up until episode 10, but good god, that ending is an incredibly frustrating, disappointing, and depressing 2, so I will grudgingly, GRUDGINGLY give this a 5 overall.
No lie, the characters are very good, with solid development for the MC, but I wouldn't have minded more than the last-minute exposition for the 2 main side characters. The overall story is great; it certainly pulled me in and got me invested.
The music is fantastic, especially if you enjoy classical. And the ending, man, the ending ruined the entire thing for me completely. Felt like getting emotionally beaten with a nail bat. I'd call the overall feel of the ending maybe something between "bittersweet" and "what the f* is this?".