After the National Tournament, the Seidou High baseball team moves forward with uncertainty as the Fall season quickly approaches. In an attempt to build a stronger team centered around their new captain, fresh faces join the starting roster for the very first time. Previous losses weigh heavily on the minds of the veteran players as they continue their rigorous training, preparing for what will inevitably be their toughest season yet.

Rivals both new and old stand in their path as Seidou once again climbs their way toward the top, one game at a time. Needed now more than ever before, Furuya and Eijun must be determined to pitch with all their skill and strength in order to lead their team to victory. And this time, one of these young pitchers may finally claim that coveted title: "The Ace of Seidou."

于国中时期最后的大赛，统合即将被废止的赤城中学参赛，却在第一回战中投出暴投，而输掉比赛的投手泽村荣纯，本来决定要与国中时期的朋友一同考入故乡的高中，却被东京的棒球名校青道高中挖角，并在那里遇见了天才捕手御幸一也，就此改变了他的人生……