User blog comment:Carebearheart/Female Dragon Slayers/@comment-2.98.224.60-20151008222118

I think that there should be a water and earth dragon slayer but as you said it's tied to the number 7 but only five are original dragon slayers so it makes sense that as it is linked to seven the original should be seven in total. And think about it, aren't the dragon slayers are linked to elements anyways