It's the typical hentai cliche. Witches who are naturally born to be always horny for sex and Demons who have infinite sex drive are locked in an eternal war. If the witch lose, she becomes the demon's personal fuck toy and be satisfied. If Witch wins, she'll get to fuck on her own terms. Winning and losing doesn't really matter.CA do it quite good with the corruption theme overall, the dialogue, hscene is just perfect, probably one of the best with this theme. But personally the whole witch thing is kinda "off" with the corruption, she's litterally a succubus, that makes the point of "corruption" a little bit invalid