Go Blackie
Beat Their Asses !

Go Black Frost! Protect Cirno!

Go Rinnosuke, Beat the big black guy, and save the loli...

Anyway... As I'm seeing things now:
Rinnosuke will proceed eliminating BF.
Once that is doe, Cirno panics, and goes EX.
After that a happy ending.

Black Frost isn't the last Frost there is though.

The great emperor comes and joins the battle !