This manga takes place in a world where warriors known as Ketsu Battlers wield swords in an unconventional way: by clenching them between their buttocks. The story follows Densuke, a boy who cannot grow stronger no matter how hard he trains. One day, while visiting his father’s grave, he discovers a mysterious blade. Rather than holding it in his hands, he instinctively clamps it between his buttocks, awakening as a Ketsu Battler. Armed with this bizarre fighting style, Densuke sets out for a legendary island called Ganjiri Island, a gathering place for all Ketsu Battlers, to test his strength and uncover the secrets of this art.

The narrative is divided into notable arcs. The first arc establishes Densuke’s origin, his discovery of the sword, and his journey toward Ganjiri Island, presented with an exaggeratedly serious tone. The second arc, known as the Tachi Jiri arc, introduces a villain named Akuzuki, who forcibly inserts these special blades into the buttocks of ordinary people against their will, creating new Ketsu Battlers against Densuke’s moral code. This arc deepens the conflict by revealing Akuzuki’s dark ambitions and the personal connection between him and Densuke, raising the stakes for the protagonist as he defends the sanctity of the Ketsu Battler way.