A man wakes up one day to find himself inside the world of Engage Hazard, a romance RPG he obsessively played in his previous life. He has been reborn as Harold, the third prince of the Dehaubalz Kingdom, a character the game describes as an incompetent, cowardly, and cruel bratty prince. In the original game's script, Harold is a disposable mob villain: he callously breaks his engagement with the duke's daughter, antagonizes the story's hero, and is ultimately defeated and executed. Worse, the game's lore states he is completely incapable of using magic, leaving him powerless to change his fate. Refusing to accept this predetermined death sentence, Harold resolves to survive at all costs. He immediately abandons the story's starting event by refusing to break off his engagement with the duke's daughter, Alexandra Chevalier. Using his detailed knowledge of the game's mechanics, hidden quests, and secret items, he begins training himself in secret. He acquires a unique shield and unlocks an enormous reserve of magic power that the original character was never meant to wield.

As Harold grows stronger by ignoring the original plot, his actions draw unexpected attention. Alexandra, who is far more powerful and dangerously devoted than the game ever revealed, becomes his staunchest ally and fiancée. Other heroines from the game, including a holy knight from a neighboring kingdom and a saintess, also begin to notice him, their interest drawn by his single-minded pursuit of strength and his refusal to follow the familiar script. The hero of the original story, Wilfred, arrives as a rival, and Harold must navigate political intrigue, hostile princes, a manipulative mastermind, and the game's own storyline events that try to force him back onto a path toward ruin. Major arcs include his training to prove himself worthy in a duel against Alexandra's protective brother, his defection from serving the arrogant first prince, and his systematic sabotage of the schemes that should have led to his execution. By leveraging foresight and forging genuine bonds, Harold works not only to escape his own bad ending but also to protect the people he has come to care for, striving to carve out a future completely different from the one the game originally wrote for him.