Leo is a warrior who was once a member of the hero Max's party, and alongside Max, Fred, and Yulia, he helped overthrow the original Demon Lord. Ten years before the events of the series, he and Max first met and formed a strong bond during a fighting tournament. Several years after the Demon Lord's defeat, Leo defected from the Kingdom of Bescar and founded the Gamma Republic in the northern region of the kingdom. While he is deeply trusted by his subordinates and the people of the republic, the Kingdom of Bescar views him as a terrorist leading an illegal occupation. His motivation stems from a desire for independence and justice, as the republic was built from untamed land that the kingdom later tried to seize after valuable resources were discovered. Leo is a martial fighter with a heightened sense of smell and formidable physical strength. His combat abilities remain as potent as they were a decade ago: a single swing of his weapon can generate massive tornadoes, and his bare body can repel both ordinary weapons and magic. In battles within the demon world, he serves as a shield for his allies, protecting them with his endurance. Leo's role in the story is that of a secondary character and former comrade who becomes entangled in political conflict with the kingdom and his former party member Fred, who now works for the Magic Bureau. Despite their differences, Leo maintains a sense of satisfaction upon seeing the reconciliation between the Demon Lord and the Hero. His development involves navigating the clash between his revolutionary ideals and the fallout from his past, as well as reconnecting with the bonds he once shared with his former party.