In recent times, labyrinths have emerged in Japan with monsters and disasters accompanying them. This led to significant changes including the creation of a new profession called "Adventurer" and their monster cards used for summoning creatures for battles within labyrinths. Utamaro Kitagawa, commonly known as Maro, is a high school student who becomes an adventurer after observing his friend achieving popularity among peers due to this new profession. Despite this, Maro faces challenges as simply being labeled as an adventurer is not enough for him to gain recognition. As such, he must actually confront labyrinths with his limited monster cards.