Flag of the Second-Stringers

(fromebookjapan):

This baseball drama depicts the tragic struggle of the players to make it to the first team under the "Flag of the Second-Stringers", a symbol of the tears of the second team players covered in blood, sweat, and mud.

Natsuki, the ace of the Fierce Tigers, who boasts having one of the best pitches in the league, somehow messes up his pitching in a game against the Chubu Tigers and gets hit by a series of pitches. So reporter Minami investigates the Natsuki strategy developed by Chubu's batting coach Haida, and...?