I don't think there'd be costumes if the concepts didn't exist, but I imagine the mythos might be a bit different.
Honestly, this outfit, I'm not sure was purchased as a complete set. Mostly just get bikini, tail, wings, gloves, stockings. Having the head wings and the ones at the end of the gloves is the harder part depending on how many demon outfits could also include them (which he still could have possibly assembled or 3d printed himself). Even if succubus' don't exist here, I find this less odd than when he had the cat boob window lingerie however long ago; who in this world is that marketed for, since supposedly every man is terrified of breasts. Was that for lesbians, or did he have it custom ordered?