Eight years ago, Francis' father, a fighter, was arrested for running away during a monster attack in Sharnwich City. Determined to rescue his father from a death sentence, Francis, a low-ranking fighter, faces challenges as the son of a traitor. Betrayed by his group, he is left to die in a monster den. Fortunately, a mysterious fighter system activates, healing his injuries and improving his abilities. Escaping danger, he discovers that the truth is hidden in a restricted area full of powerful monsters. Francis must confront fish lizards and level up to uncover the truth!