Akuyaku Reijou, Seizon no Kagi wa Saikyou Ogikei-sama no Yandere Power desu

At fourteen years old, Erika mysteriously finds herself transported to another world where black hair is feared and despised. Alone and vulnerable, she is rescued by Daryl, the black-haired head of the infamous Dark Duke family, who takes Erika into his household as his adopted younger sister. Eventually, Erika realizes something terrifying: this world closely resembles a shoujo manga she read in her previous life, and “Erika” is its villainess. According to the original story, Erika will become a candidate to marry the First Prince, bully the story’s heroine, and ultimately meet a horrific end alongside her adoptive brother. Daryl’s obsessive love for Erika eventually drives the two into a fiery double suicide. Erika has absolutely no intention of letting that happen. Determined to avoid her predetermined destruction, she sets out to change the story while confronting the intensely possessive affection of the brother who saved her. But as Erika learns more about Daryl and the world around them, she begins to suspect that perhaps she wasn’t brought to this world simply to save herself. Maybe she was brought here to save him as well. A villainess fantasy romance about a girl fighting against her bad ending alongside the dangerously devoted yandere brother who was originally destined to die with her.