Sena Kobayakawa

Sena begins timid, submissive and deeply conditioned to avoid conflict. He has spent years accepting errands and bullying rather than resisting, partly because Mamori habitually intervened on his behalf. His politeness and empathy remain intact as he grows stronger, but his willingness to stand his ground changes dramatically.

Football gives Sena something he chooses for himself. He initially fears powerful opponents and doubts whether he belongs among serious athletes, yet repeatedly returns to the field because he enjoys playing and wants to help his teammates.

He is also highly respectful of rivals. Rather than treating opponents simply as enemies, Sena studies what makes them strong and frequently uses those encounters as motivation to improve.

Sena's defining ability is acceleration and running speed. His experience as an errand boy taught him to weave through crowded streets while maintaining momentum, giving him both straight-line speed and instinctive evasiveness before he understands football technique.

His running develops into specialized moves. The Devil Bat Ghost combines extreme speed with sharp cutting to evade tacklers without fully stopping. The Devil Bat Hurricane adds a spinning movement, while the Devil Stungun uses an arm extension to keep a defender away during a run.

His 40-yard dash eventually reaches approximately 4.1 seconds under ideal conditions. Sena also develops stronger legs, greater endurance and better reading of blocks through Deimon's training, especially the Death March in the United States.

Hiruma discovers Sena while watching him escape a group of bullies and forces him into the football club. Because Deimon wants to hide its new runner from future opponents, Hiruma creates the fictional Eyeshield 21 identity and claims that the masked player is a mysterious Notre Dame athlete.

Sena initially tries to separate his ordinary self from the fearless player represented by the helmet. As his confidence grows, that distinction becomes increasingly unnecessary.

Sena eventually reveals publicly that he is Eyeshield 21 and begins competing under his own identity. His rivalry with Panther, Shin, Riku and eventually Yamato pushes his speed beyond what he could achieve by simply relying on natural talent.

He ultimately helps Deimon win the Christmas Bowl and later continues pursuing American football beyond high school, turning what began as forced recruitment into the defining competitive passion of his life.

Mamori Anezaki is Sena's childhood friend and longtime protector. Sena cares deeply for Mamori Anezaki, but football forces him to demonstrate that he can make difficult decisions and face danger without always relying on her.

Youichi Hiruma discovers Sena's speed and forces him into the Devil Bats. Although Youichi Hiruma's methods terrify him initially, Sena comes to trust his quarterback's judgment.

Ryokan Kurita is one of Sena's first genuine friends at Deimon and provides a welcoming introduction to football.

Tarou Raimon becomes Sena's closest same-year teammate. Sena recruits Tarou Raimon after recognizing that his extraordinary catching talent has a natural place in American football.

Riku Kaitani is Sena's childhood friend and the person who originally teaches him how to run effectively. Their reunion turns that childhood lesson into an athletic rivalry.

Seijuro Shin becomes one of Sena's defining rivals. Sena repeatedly measures his development against Seijuro Shin's speed, strength and disciplined technique.