If you want an obscure NES RPG, you can't get much more obscure than the Legend of the Ghost Lion.
Game was an Dragon Quest-ish RPG made Kemco, a developer not known to make RPGs at all, starred a little girl as the main character, and was released for the NES in 1992 and had no sequels and was basically never heard from again.
As you can imagine, it didn't sell very well in North America. I don't think there's another NES RPG that even comes close to being that obscure.