I can't see why it would be a separate category. Dragon Warrior 3 uses metal slime manipulation, along with other manipulations, as the normal run.
I say don't make a new category. My guideline is that a category should only be split when there are enough people to do runs in both sides of the split, and while that's the case in Japan, it's not so here.
Also, I'm happy to see so many people interested in the game!
Also, I'm happy to see so many people interested in the game!