The world of Oreca card battles is a popular and exciting contest among kids, but the fantastical competition takes a dangerous turn when the monster characters on the cards mysteriously begin to disappear and manifest in the real world, causing chaos. The story follows a spirited boy named Fire Orega, who loves these Oreca competitions. After he witnesses the cards materializing, he encounters a mysterious talking chest or creature named Pandora, who grants him the power to summon and battle with real Oreca monsters.

The setting blends the everyday world with the sudden intrusion of fantastical creatures, as Fire and other young tamers, such as the Oreca Youth Scouts, must learn to control their new abilities. Alongside friends like the frog-like monster Kerogon, the knowledgeable Data Uchiki, and the strong-willed Gantetsu Kurata, Fire uncovers the secrets behind these events. The central conflict escalates as it is revealed that the legendary Twelve Dragons have been stolen by a powerful Demon King, who threatens the peace of both the human and monster worlds.

The narrative arc focuses on Fire's journey to master his summoning power and his quest to battle the Demon King's forces. To protect the Oreca world and restore the cards to their original form, Fire must fight in real-life Oreca battles, ultimately aiming to take back the twelve dragons from the clutches of the devil king. The series explores themes of courage and friendship as Fire grows from a simple fan of the card game into a true hero capable of defending his world. The story was followed by a sequel manga titled Maō Da Ze! Oreca Battle, which continues the adventures.