The Fall Tournament Begins!
Seido ends up in the fall's most competitive bracket. In order to have any chance to advance they will have to overcome regular national tournament participant Teito, a school that has advanced to nationals 27 times and won in twice. As if that weren't enough, Teito has an unrivaled first year pitcher who can see the strike zone three dimensionally. Coach Kataoka comes up with a strategy that could give Seido the ability to advance if they can pull it off, and he delivers a few words to Sawamura when Sawamura asks if he can switch to being a sidearm pitcher.
Aired 27/04/2015EP 4 - The Fall Tournament Begins!

Ace of the Diamond Second Season
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."
[Written by MAL Rewrite]