Hakushaku Reijou wa Yandere Dannasama to Ateuma Scenario wo Kaihi suru!!

One day, Sierra Digitalis remembers her past life. She discovers that she has been reincarnated as a rival character in an 18+ otome game! To escape this troublesome role, Sierra decides to fall in love with a man who has nothing to do with the game. With the help of a spirit, she meets a handsome black-haired man who is exactly her type, and they fall in love... or so she thinks, but the man she loves has a secret that could shake the world...!?

(Source: Kodansha, translated)