Kaifuku Jutsushi no Yarinaoshi, also known as Redo of Healer, is a dark fantasy anime series that follows the story of Keyaru, a healing magician who is exploited and tortured by others. He decides to use the Philosopher's Stone to go back four years in time and take revenge on those who wronged him. The series explores themes of vengeance, power, and redemption, offering a controversial and intense narrative.