Gao Mikado, a student in sixth grade at Aibo Academy's Elementary Division, teams up with Bal Dragon - a dragon that hatches from a mysterious egg - to participate in the "World Buddy Cup" and become the most dominant fighter worldwide. This card game allows monsters to befriend people, prompting Gao and Bal to face off against their strongest adversaries, including Tasuku Ryuenji - a former Buddy Police officer - and the seemingly unbeatable pair of Gaito Kurouzu and his buddy monster, Abygale, commonly referred to as Black Death Dragon.