"Redo of Healer" is a dark fantasy anime series centered on Keyaru, a young healer who endures years of physical and psychological torment after being exploited for his restorative abilities. The story begins in a world where healers are rare and often forced into servitude. Keyaru, possessing the unique ability to heal others by absorbing their pain and memories, is enslaved by the kingdom’s royalty and subjected to relentless abuse, including torture, manipulation, and betrayal by those he once trusted. After years of suffering, Keyaru discovers a way to rewind time using a powerful artifact, the Philosopher’s Stone. He seizes this opportunity to rewrite his past, vowing to exact revenge on those who wronged him.

Upon returning to the past, Keyaru retains all the knowledge and skills from his previous life, allowing him to manipulate events and people to his advantage. Adopting the alias "Keyarga," he embarks on a calculated path of vengeance, targeting individuals such as Flare, the princess who enslaved him; Bullet, a sadistic warrior; and Blade, a merciless assassin. Keyaru’s methods are ruthless, often involving psychological manipulation, physical violence, and morally ambiguous actions. Along the way, he forms alliances with other characters, including Freia, a brainwashed version of Flare, and Setsuna, a demi-human seeking revenge against her own oppressors. These relationships are complex, blending loyalty, manipulation, and mutual benefit.

The narrative explores themes of retribution, trauma, and the cyclical nature of violence, presenting a morally gray protagonist whose actions challenge traditional notions of heroism. Keyaru’s journey is marked by a relentless pursuit of justice, albeit through morally questionable means, as he seeks to dismantle the corrupt systems and individuals that perpetuated his suffering. The series delves into the psychological toll of his experiences, highlighting the impact of trauma on his worldview and actions. "Redo of Healer" is characterized by its unflinching portrayal of dark themes, including abuse, revenge, and the consequences of unchecked power, making it a polarizing yet thought-provoking entry in the dark fantasy genre.