[Permission (Dendou Monaka)] Succubus no Daibouken ~Yuusha-sama no Nakama ni Natta Furi shite Hime-sama to no Shoya ni Muriyari Ochinchin Netochatta Ohanashi~ [English]
So her master plan was to let him achieve his goal of defeating the demon king and marrying into royalty so that she could trick him into having tons of sex. Not seeing the evil part.
@Boomer30569 I mean...now she has the world's strongest person under her complete control. She essentially has the princess as hostage (and she'll probably control her later too). She's basically the new demon king and has the world in her palm lol