No worries!
Evil Kaiser Dragoon is pretty decent for a dark party; however, he is almost useless in any other element. If you plan to go dark, there's no harm in keeping her for now. Wait and see if you can get a more versatile SSR Eidolon or a good SR princess.
And yes, there are SR princesses in the pre-reg. I did a summary on some of the best SR princesses a few pages back.
My kept SR princess:
Also, they're called Kamihime. Since someone else started calling them princesses in this thread, I just went with the flow as to not confuse people. But I should probably change it to Kamihime from now on.