Thanks for the replies, everyone! The Last Comer is probably my favorite fangame from what little my old computer would let me play it, and I appreciate your help.
@Helepolis: Well, as I said, that is what I would love to do if only every program I tried to open with Japanese settings didn't crash. Chinese works just fine for other games though, this is the only game where something's amiss. Once I figure out how to upload pictures I'll post the messages that appear whenever I try to simply open it and whenever I open it with the Applocale Chinese setting. As for the Japanese setting, it's just a plain ol' "Program has stopped working" message so there's nothing worth noting there. I'm still pretty sure opening it in japanese is the key, but I first gotta find out why it's the only one that crashes, for ANY program. Still, thanks and I did not modify anything, don't worry.
@Karisa: Oh you mean like changing the language in the Language for Non-Unicode Programs section in the Administrative tab in the Region window, right? I kinda remember trying it out before but I'll see if it works this time. Thanks and I'll keep you updated. OH! I forgot to mention: I got Windows 8 in Spanish, my native language, I dunno if that's of any importance to this issue, but sorry if I got the names wrong.
UPDATE: Did not work, it just crashes immediately after opening it, as if I had opened it with applocale in japanese setting. I would appreciate more suggestions.
LATEST UPDATE: IT'S WORKING NOW! I felt the need to post how it was fixed as well as words of gratitude to my brother who came up with the idea and the user WanderingShadow of this very same forum. The solution? Installing the English patch! My guess is that doing so made the dialogue "understandable" to my computer and now it doesn't detect that a scene is missing. I also can tell you that Applocale isn't even necessary; my OS is operating in spanish but The Last Comer still opens and plays! well, I had to download danmakufu again because one of my copies was seemingly faulty, but I think that was an entirely different problem.
Well, any way I look at it, part of the credit on this goes to the Shrine Maiden forums for helping, thank you everyone.