Well, that's one grid that can't use R weapons for the time being... finally got around to it:
next target is my fire one.... then wind and dark (depending on which seems more worthwhile). Thunder and water.... i don't have much hope in their kami selection...
it's a case of "just get as far as you can". Guild Order is designed the same way (and the union raids technically).
but you can beef up your teams and grids as you go. so farming the current Koihime crossover might help since there's still magic jewels and stuff