Sena Kobayakawa has just started attending Deimon Private Senior High School, and he's already getting picked on by bullies. His saving grace is his incredible speed, which he can use to escape sticky situations. Sena's talent is noticed by Yoichi Hiruma, the captain of the school's American football club, and so he forcibly recruits Sena as the team's running back under an alias: Eyeshield 21.

Although the manga this game is based on, Eyeshield 21, revolves around American Football, Devilbats Devildays follows the misadventures of Sena and co. while they're off the field. The main game has the player going through text-adventure style paths which lead to different endings as well as playing a variety of mini-games.