"Basquash!" is set in the futuristic world of Earthdash, where the sport of Big Foot Basketball, or "Basquash," has become a global phenomenon. The story centers around Dan JD, a skilled mechanic and basketball player living in the impoverished slums of Rolling Town. Dan harbors a deep resentment for the sport due to a tragic accident involving his sister, Coco, who was left paralyzed after a Big Foot robot malfunctioned during a game. Despite his disdain, Dan is drawn back into the world of Basquash when he encounters a mysterious girl named Sela, who encourages him to use his talent to bring hope to his downtrodden community.

Dan reluctantly joins forces with his friends, Iceman Hotty and Flora Skybloom, to form a Basquash team. Their goal is to compete in the prestigious Big Foot Basketball League and challenge the elite teams from the floating city of Mooneyes, which symbolizes wealth and privilege. As the team progresses, they uncover the darker aspects of the sport, including corporate greed and the exploitation of players. The narrative explores themes of social inequality, redemption, and the transformative power of sports.

Key characters include Dan JD, whose journey from a reluctant participant to a passionate leader drives the story; Iceman Hotty, a former professional player seeking redemption; Flora Skybloom, a determined athlete with a mysterious past; and Sela, whose connection to the origins of Basquash becomes pivotal. The series also features antagonists like the corporate magnate Haruka, who manipulates the sport for profit, and the enigmatic Echizen, a rival player with a personal vendetta against Dan.

The plot intertwines high-energy basketball matches with personal struggles and societal commentary, culminating in a climactic showdown that challenges the status quo of Earthdash. The series balances action, drama, and character development, offering a compelling narrative that appeals to fans of sports anime and futuristic storytelling alike.