Riku Kaitani

Riku is confident, competitive and socially direct. He dislikes bullying and intervenes when stronger people mistreat someone weaker, the same instinct that originally leads him to help Sena.

Unlike Sena's initially hesitant approach to competition, Riku is comfortable with his athletic ability and enjoys testing his speed against strong opponents. Their reunion therefore gives Sena a rival who understands exactly where his running began.

Riku also has a strong sense of pride in Seibu. He is not simply an individual speedster; he trusts the Wild Gunmen's offensive system and the teammates whose passing and receiving create space for his runs.

Riku's signature technique is the Rodeo Drive, a running style built around rapid changes of direction and body movement. Rather than relying solely on straight-line acceleration, he uses footwork to evade defenders while maintaining speed.

His 4.5-second 40-yard dash makes him one of Japan's fastest high-school running backs, although Sena eventually reaches a higher top speed. Riku compensates with refined technique developed through years of deliberate running practice.

He also plays safety, giving him defensive responsibilities and allowing his speed to be used in pass coverage and pursuit.

Riku meets Sena during childhood and sees him being bullied. He teaches him how to run so that he can escape trouble, unaware that Sena will spend subsequent years using those lessons to become an exceptionally efficient errand runner.

The two are separated when Riku's family moves. When they meet again in high school, Riku has become Seibu's running back and quickly recognizes the movement of the mysterious Eyeshield 21.

Their eventual game turns the childhood teacher-student relationship into a direct competition. Sena must demonstrate that the running Riku first taught him has evolved into a style of his own.

Sena Kobayakawa is Riku's childhood friend and former pupil in running. Their high-school reunion develops into a friendly rivalry built on the enormous distance Sena Kobayakawa has traveled since those early lessons.

Kidd is Seibu's quarterback and directs the offense in which Riku operates as a principal rushing threat.

Tetsuma Jo is another central member of Seibu's offense, with his receiving ability complementing Riku's ground game.

Maruko Himuro approaches Riku before Seibu faces Hakushu because she fears the injuries that could result from confronting its power-based style.