I remember being gifted this weird JRPG for the Gameboy that was not even localized, and being a stubborn kid I randomly went through its japanese menus trying to see what each thing did, but gave up in the end. Years later I had a flashback and went to YouTube, only to find it was actually an incredibly mediocre Gundam RPG called Lacroan Heroes. It’s a long shot, but that’s the most obscure JRPG I know of for the Gameboy, maybe that’s it?
Read my edit, I found it!!! :D