I have the original disc and still could not run the game even with Japanese Locale. So, you can also try running the game with Locale Emulator if you cannot start it. And if you are downloading from here, don't forget to edit the「Current」path in the「install.inf」file too.「Current」is where the「Start.exe」is located. Good luck. : )

I'm not play yet, but every アトリエかぐや's game not only to need change Japanese Locale but you also need to change Region format to Japanese too.

I installed the game on a machine that runs with Japanese Locale. Japan region and (UTC+09:00) Osaka, Sapporo, Tokyo time zone. It still does not works. I have not encountered the same issue with their older titles with similar Windows settings, but I have not had any success running their recent titles. So, that is just a workaround if you cannot run it. Well, it's good if you can run the game with your current settings. : ) Maybe my Windows is not Japanese enough to run the game XD

: I had similar issues because I only had my system locale set to Japanese and used to only swap timezone and Region format for the few titles that required it back then - it was notably Hadashi Shoujo games and a handful of other random games. Once Atelier Kaguya titles "joined the mix" I decided to just leave it like that, even if it took some time getting used to having to math out my actual time if I decide to check the time on my computer. I know there's been at least a single weird case where I can't run it normally regardless of settings, but with the settings AND Locale Emulator it works. Your first message didn't really specify if you had tried that yourself or just recommended others to use LE, but if you haven't then just in case it might be worth giving it a try.

...Have you guys, "disk owners"; actually inserted/mounting the disk when trying to play or launching the game?