>>713474651At some point in the game you need to gain entry into hell, but it's guarded by different magic wards that need you to be "sinful" in order to bypass them. One of the wards is lust, and it tells you it wants you to fuck a demon. You can fuck an enemy demon succubus general as part of the main story, or you can "no way, fag" her and do a side quest to fuck your demoness rival instead.