Eyeshield 21 is a Japanese manga series written by Riichiro Inagaki and illustrated by Yusuke Murata. The series tells the story of Sena Kobayakawa, an introverted boy who joins an American football club as a secretary, but after being coerced by quarterback Yoichi Hiruma, becomes the team's running back, wearing jersey number 21 and an eyeshield to conceal his identity. Inagaki chose American football as a central subject of Eyeshield 21 after realizing that it fit perfectly with his idea for the series.

Sena Kobayakawa , commonly referred to just as Sena (セナ), is a fictional character who is the protagonist in the manga and anime series Eyeshield 21, created by Riichiro Inagaki and Yusuke Murata. In the series, he is a first-year Japanese high-school student who becomes a gofer to avoid being bullied. His running ability improves and he is noticed by Yoichi Hiruma, the American football team's captain, who gets him to join the Deimon Devil Bats as the team's running back under the name "Eyeshield 21". Sena has appeared in other media from the series, including video games, original video animations (OVAs) and light novels.