Aha, now this is revealing (no pun intended). Prim and proper Shanghai is wearing grandma bloomers and can therefore act with her full range of movement, no considerations necessary, while hardcore Hourai wears a pantyhose with (assumed) panties but has to conveniently position her legs or the speedlines of her attacks so not to show them pantyshots to the readers.

It's hilarious how one can infer so much about the characters simply through their choice of underwear.