Invincible Dad of Another World - Chapter 6

Upon meeting the girl who would become her adopted younger sister, the duke’s daughter Christina regained memories of her previous life. Through those memories, she learned that her new sister, Mishuli, was the heroine of a certain story. And though the story depicted a Christina who abused her sister, the real Christina turned into a siscon who spoiled Mishuli to no end.

After his death, Bern awakens 10 years into the past as the third prince of Kailis, the enemy country.

A back-to-basics(?) monster evolution novel.