在这部王牌投手 振臂高挥动画/运动片中,由于初中不幸的遭遇，个性十分要强认真的少年三桥廉（代永翼 配音）放弃了良好的升学条件，决心单枪匹马远赴位于埼玉县的西浦高校就读。社团招新的当天，在半推半就之下，三桥加入了刚刚转型成功的棒球部担任投手的位置。一段高中校园中的热血棒球史诗就此展开。
棒球队中，三桥结识了一帮志同道合的好友，在充艰苦的训练和激烈的比赛中，彼此结下了深厚的友谊。个性大大咧咧但又不失细腻的捕手阿部隆也（中村悠一 配音），叛逆不羁又格外可靠地外野手花井梓（谷山纪章 配音），视力惊人的三垒手田岛悠一郎（下野纮 配音）等人，在教练百枝麻里亚（早水理沙 配音）的带领下，他们向甲子园的荣誉不断的前进着。
Follows Ren Mihashi, who had previously excelled as his middle school baseball team's ace pitcher, due to his grandfather's connections as its manager. As he graduates to high school, whose baseball team his grandfather does not manage, he initially does not believe he is good enough to succeed at baseball, however, but assisted by his friends, he grows in stature, confidence and skill, helping his team excel with his own ability.
十分实用的棒球动漫。此间的少年——写在《大振》第二季之前。当大叔重新变回大叔——深夜围观大振声优见面会之后。那些美好之《王牌投手之振臂高挥》。青春啊~！。题外话（ 关于A3 ）。无法忘记的那年夏天。像SD一样好看的体育作品。又见热血的棒球青春。举重若轻，温和平实。
