Captain (Akio Chiba)

(from ebookjapan):

A hot-blooded sports manga in which the captain of a weak baseball team and his club members work hard and grow into the strongest team in the game. Takao Taniguchi, who has transferred to Sumiya Second Middle School, changes into the uniform of his former school in order to join the baseball team's practice.

When the members of the baseball team realize that it is the uniform of Aoba Academy, a prestigious baseball school, they assume that Taniguchi is a big name player. However, Taniguchi, when he was at Aoba Academy, was a poor second-team substitute player who was...!