The protagonist Sachie is reincarnated into another world. After she has her first night with her fiancé Kazuomi, her memories of her previous life come flooding back and she comes to realize that this is the world of an All-Age Otome game that she played in her previous life. While she becomes somewhat sentimental about her family and friends which she has left behind, thanks to Kazuomi's kindness, she gains the determination to live her new life in this new world.
"Today we are going to have a threesome. Oh, I forgot to mention, but I so want to see you getting ravaged by another man." Kazuomi suddenly comes out confessing that he has a cuck fetish, and begs her to do it with the butler for him? Bewildered the heroine is swept away by the torrent of her fiancé's perverted desires.
"Oh my, it's not very becoming of you to writhe in the pleasure provided by another man right in front of your fiancé." Thus the curtain was raised on an abnormal sex life with a perverted noble and a sadistic butler.

There is a TL and R18 version.

Official Translations:
English, S.Chinese, T.Chinese, Korean