The series takes place during the year 2030, in Choutokyo, Japan. Through the game "Buddyfight", humanity is able to interact with the residents of other worlds: Buddy Monsters. Chosen humans (known as "Buddyfighters") become "Buddies" with Buddy Monsters to play the game. Gao Mikado is a student at Aibo Academy. His life changes when he meets the son of the hero of the Dragon World: Drum Bunker Dragon (whom he nicknamed 'Drum') that he drew from a pack in class one day.