Chiisaku Furikabutte, lit. “Small Windup”, was published in Afternoon between the tankobon publications of volumes 15 and 16 and during the 2011 hiatus, and it is a series of specials about the lives of Oofuri characters. (Nice Pitching!)

Mihashi moves on to high school convinced he is a lousy baseball pitcher. There he meets the catcher Abe and the team manager Momoe who together work to make Mihashi and the team shine.
(Source: ANN)