Drop rate statistics - the Sengoku'ing

hmm there might be a ceiling on the number of coins you get? so that donxon can get more of your mez0r3z.

There is.
Each enemy drops one coin, except Kanna and Hayato (who can drop up to 6) and Ranmaru (who can drop up to 12).
The total can't go over 76.

So as far as our research goes, we can't learn anything about high drop rates. But we have nothing better to study at the moment.