Mondo Oooya is one of the main protagonists of the anime series. He is an ordinary elementary school student who attends a local public school and has a deep passion for the Monster Collection trading card game. His life takes a dramatic turn when he becomes involved with the experiments of Professor Ichiroubei Hiiragi, his classmate's father, and is recruited as a Mon Colle Knight alongside his friend and love interest Rokuna Hiiragi. Despite the initial shock of discovering a parallel dimension known as Mon World and the silly outfit he is given, Mondo adapts quickly to his new role. He is a determined and courageous boy with a great deal of endurance, often serving as the physical strength of the team. His primary motivation is to gather the six Mon Monster Items in order to unite Mon World with the human world and bring lasting peace between both realms. Mondo has a particular fondness for dragons, but he is most frequently seen with a small winged horse that he meets early in the series, a chibi Pegasus that later grows into a full-fledged pegasus. The two form a deep and loyal friendship, and Mondo cares for the creature greatly. In terms of personality, Mondo is outgoing and sees the world through a lens that romanticizes characters in need. When he encounters attractive girls who appear to be in trouble, he instinctively shifts into a hero mode, sometimes removing his shirt in the process. However, these girls are rarely in genuine emotional distress, and Rokuna often intervenes by physically bringing him back to reality. His frequent flirting with other female characters is not born from a lack of regard for Rokuna; rather, it is an impulse he cannot seem to control. Despite these tendencies, Mondo is fundamentally good-hearted and fully committed to the mission. He also develops a rivalry with the antagonist Prince Eccentro, who seeks to collect the Monster Items for himself in order to dominate both worlds. Mondo plays a key role in the ongoing battles against Eccentro and his underlings, helping to prevent their schemes from succeeding. Over the course of the series, Mondo gradually becomes more integrated into the Hiiragi household, spending more time with the family as the story progresses. Very little is known about his home life before the events of the series. A notable physical trait is the criss-crossing bandage on his forehead, the origin of which remains unexplained. Mondo wears different outfits depending on the world: in Mon World, he dons a dark blue tank top, white gloves, shorts, and brown boots, while in the human world he typically wears a green and white t-shirt, blue shorts, white socks, and red and white sneakers. His main ability as a Mon Colle Knight involves merging with monsters and controlling them in battle, often accompanied by the chant "With us, you can do it!" He also uses spells to aid in combat. Through his courage and persistence, Mondo helps to build understanding and cooperation between the human world and the magical creatures of Mon World.