^^ Reisen is actually infamous for just how much porn she shows up in, to the point where, "Useless bunny, only good for sex" is something of a meme in the (straight, male, unwashed) Touhou fandom. Heck, it's even indirectly referenced in-universe- one of the dialogues in Scarlet Weather Rhapsody during a Reisen vs. Aya match has Aya saying that she can't write about Reisen in her newspaper, because it would bring down the standards and dignity of her publication (which is meant to be a veiled Playboy Bunny joke).
I personally find it kinda sad, because Bun is a wonderfully complex character and one of the few 2hus who could be in a loving relationship without glaring issues of insanity, hunger, duty, species issues, immortality or yokai-logic getting in the way.