Kousuke Ueki, a middle school student, is chosen by Candidate Kobayashi to participate in a supernatural tournament where individuals wield unique powers granted by their sponsors. The tournament’s purpose is to determine the next King of the Celestial World, with each candidate selecting a human representative to fight on their behalf. Ueki is granted the ability to turn trash into trees, a seemingly mundane power that he creatively uses in combat. His sponsor, Kobayashi, is a laid-back and eccentric figure who provides guidance but often leaves Ueki to rely on his own ingenuity.

The narrative unfolds as Ueki and his classmates, including his close friend Ai Mori, become entangled in the tournament’s battles. Ueki’s primary motivation is to protect his friends and uphold his sense of justice, which often clashes with the morally ambiguous nature of the competition. As the story progresses, Ueki faces a variety of opponents, each possessing distinct and often bizarre abilities, such as transforming objects into iron or manipulating sound waves. These battles test not only Ueki’s combat skills but also his resolve and moral compass.

A significant subplot involves Ueki’s discovery of the darker aspects of the tournament. Many participants are coerced into fighting, and losing can result in severe consequences, including the erasure of one’s talents or even their existence. Ueki’s determination to challenge this system and protect his friends drives much of the narrative tension. Along the way, he forms alliances with other participants, such as Rinko Jerrard and Hideyoshi Soya, who share his ideals and contribute their unique abilities to the group’s efforts.

The series balances action-packed battles with moments of character development and humor. Ueki’s growth as a fighter and a person is central to the story, as he learns to harness his powers more effectively and confronts increasingly formidable opponents. The tournament’s structure allows for a diverse array of antagonists, each with their own motivations and backstories, adding depth to the conflicts.

As the tournament progresses, Ueki uncovers the true intentions of the Celestial World and the manipulative forces behind the competition. The final arcs focus on Ueki’s confrontation with the tournament’s overseers and his efforts to dismantle the oppressive system. The resolution ties together the themes of justice, friendship, and perseverance, culminating in a climactic battle that determines the fate of both the participants and the Celestial World itself.