The story follows Ousuke Soma, a super high school tennis prodigy who has just won the national championship. Immediately after his victory, he is suddenly summoned to a fantasy world as a hero by a mage named Elisha. In this other world, where dragons, demon armies, and knight orders pose genuine threats, Ousuke finds the situation far less impressive than the high school tennis nationals he just conquered.

Ousuke wields his tennis skills as his primary power, and in this world, tennis has become the most extraordinary superpower. He is able to kill a dragon with a single blow, annihilate an entire army of demons, and easily defeat the elite knights of the realm, all using techniques from his tennis repertoire. Elisha, the mage who summoned him, is constantly astonished by his abilities, watching in disbelief as his tennis balls multiply and split, or as he enters a Zone that transcends normal understanding.

The initial narrative arc establishes Ousuke’s overwhelming power as he demonstrates that his national-level tennis skills far surpass any magic or swordplay in this new world. His casual mention that such abilities are required skills at the national level leaves his allies bewildered. The central conflict introduces a surprising twist when it is revealed that the demon king of this world is not a dark sorcerer or warrior, but also a tennis player. This sets the stage for the primary narrative arc: a climactic tennis match between the summoned hero and the demon king, where the fate of the world will be decided not by conventional warfare, but by an otherworldly tennis showdown. The story is a super tennis fantasy that discards common sense, written by Kota Nozomi with illustrations by Yūnagi.