The Knight in the Area

Believing himself to be useless at soccer, Aizawa Kakeru instead becomes the manager of his school's soccer team, while his brother Suguru is its ace, and is even good enough to represent Japan in the championships. However, Kakeru may have a yet unknown strong talent within himself that only his brother Suguru can see, and they often get into arguments over Kakeru's denial of his skills. Things are made more complicated with the return of Nana, an old friend of theirs that Kakeru has a crush on.

Synopsis from Anime News Network