His violent nature earns him the nickname Oniko, the demon child, and his days are consumed by brawling. That changes when police officer Komiya takes him into custody. Seeing Ryouichi attack even an officer to protect a friend, Komiya decides that kendo is the only way to rehabilitate him. Ryouichi begins the sport purely to one day defeat Komiya, but a betrayal by his own friends leaves him severely wounded, permanently damaging his right arm. Determined to rise beyond the injury, Ryouichi sets out to master the jodan stance as a one-armed swordsman.

Ryouichi enters Kousen High School and joins its kendo club, only to find a near-defunct team made up of the timid captain Hazama and two inactive members, Takao and Sumiyoshi. With the reluctant help of the club advisor Sasazuka and the talented but aloof Ichigaya, Ryouichi pushes the ragtag group into their first serious match against the powerhouse Souei High School. That early clash forces each member to confront their own limitations and awakens in Ryouichi a genuine hunger for the sport beyond revenge.

As the team trains for the district qualifiers, Sasazuka arranges a practice match against the golden generation of Kousen alumni, a group that once led the school to national glory. Ryouichi faces Kunryo, a police officer and the strongest of those alumni, who challenges him to see kendo not just as a fight but as a path of growth. The lessons from that match reshape the team and give Ryouichi new direction.

The district tournament brings a string of brutal opponents, including a team that treats kendo as a blood sport and a rematch against Souei where Ryouichi must overcome his emotional ties to Komiya. A loss forces the team to fight through the repechage bracket just to reach the Tokyo metropolitan tournament. After the tournament, Ryouichi seeks out Komiya at his dojo and meets Shoumaru, a devoted student of Komiya, giving him a deeper understanding of the master's style and of his own place on the path.

Determined to grow further, Ryouichi trains under Kunryo's instructor to master the strike of nothingness, a technique that hides all killing intent. His progress is cut short when Komiya is hospitalized after a duty accident. Unable to continue as a police officer, Komiya tells Ryouichi that this is his moment of departure from the master's shadow. The story then moves into the Gyokuryuuki tournament, a high-level team competition. Ryouichi is forced into a desperate five-match streak against the powerhouse Nadeshiko International High School. Fight after fight pushes him to the brink, and as his body gives out, past trauma resurfaces, leaving the outcome hanging on whether he can break through his own limits.