meh, I only leveled the Shiki's. With massive crits and counter-attacks, not to mention their stupid dodge rating, I didn't need anyone else. Akiha and her AT field were lols, but up since she couldn't attack close up, I didn't bother.
I do have much love for Rin, so I tried leveling her, but it went so very slowly till she became Kaleido Ruby, but she was still too weak...too little HP.