Yes, drop rates blow outside of 3 kings. I have to squeak my alt account through getting 1 star each time and i still get more than any other map.
That's weird. Of all the times I've run Ryuujin King the only time I didn't get 5 MC was when I didn't kill the bottom wizard when I accidently inverted my units. The second MC drop has crap rates, but the first might as well be 100% for me.