"Reset! The Imprisoned Princess Dreams of Another Chance!" is a fantasy manga that centers on Princess Rosemarie, the daughter of a tyrannical king who rules the Kingdom of Valschein. After years of enduring her father's oppressive reign, Rosemarie is falsely accused of treason and imprisoned. Facing execution, she reflects on her life, filled with regret and sorrow over her inability to change the kingdom's fate. However, at the moment of her death, she awakens to find herself transported back in time to her childhood, retaining all memories of her previous life.

Determined to alter the course of history, Rosemarie uses her knowledge of future events to navigate the political intrigue and power struggles within the royal court. She seeks to prevent the tragedies that befell her family and kingdom, including the rise of her father's tyranny and the eventual collapse of Valschein. Her actions attract the attention of key figures, including her loyal knight, Leonhart, and her childhood friend, Prince Cedric of a neighboring kingdom. Rosemarie must balance her desire for redemption with the complexities of royal politics, alliances, and the moral dilemmas of altering the future.

The story explores themes of second chances, the weight of responsibility, and the consequences of wielding power. Rosemarie's journey is marked by her growth from a passive observer of her fate to an active participant in shaping her destiny. The narrative delves into the intricacies of court life, the relationships between characters, and the challenges of changing a predetermined future. Through Rosemarie's efforts, the manga examines whether it is possible to rewrite history and whether the sacrifices made along the way are justified.