Any idea why Wakaba is supposed to have BDSM hobbies? I don't see anything in her lines related to that.

The Wikia said her badly damaged line is "痛いぞ……だが、悪くない…… /It hurts... but, I don't mind..."

I assume it's the same conclusion that Tenshi got the masochist schtick.

From her "badly damaged" line, maybe?

Wakaba, once badly damaged, said:

It hurts... but, I don't mind...

Of course this is just my guess, but hopefully she won't become another Tenshi, though.

(Edit) Welp, I got ninja'd. It's alright tho.

Mucho gracias, you two.