Charlotte Hiber, a kind-hearted duchess's daughter, had a bright future in the Grandia Kingdom, but her life took a dark turn when her father took in her cousin, Lily. Her once supportive family and friends turned against her, and even her beloved fiancé, the crown prince, fell for Lily. Abandoned and mistreated, Charlotte is visited by an injured monster who offers to help her take revenge on those who wronged her. This is the story of a Japanese high school boy who reincarnates as a monster in another world, grows stronger, and executes retribution across the land.