[ZeroWolf]

Not to be rude but nothing in the definition of Heroine matches what "providing emotional support to the protagonist". The literal definition is as follows:
"a woman who is admired for having done something very brave or having achieved something great"
The second definition matches Rinne even better:
"the main female character in a book or film, who is usually good"

So I don't quite understand why making Rinne a rider (which I liked) makes her a bad Heroine.