In episode 17 of Mix - Meisei Story S2, the plot primarily revolves around the National High School Baseball Championships, East Tokyo Division. The episode begins with a casual conversation among the characters, discussing the upcoming games and potential outcomes.

The quarterfinal lineup of the tournament is announced, and it’s noted that only the seeded schools remain. The expected final is set to be between Seinan and Kenjo, with Kenjo being the crowd favorite. However, the characters express a desire for a surprise and hope for a Meisei vs. Kenjo final.

The episode then shifts to a series of baseball games. The first game is between Kenjo and Houkaidai Ni, with Kenjo emerging as the winner. The game is one-sided, highlighting Kenjo’s strong lineup and the outstanding performance of their cleanup hitter, Akai.

The next game is between Shirayama and Toushu. Toushu, the previous year’s champion, manages to pull through in extra innings, setting up an exciting semifinal against Kenjo.

The focus then turns to Seinan vs. Akanodai. Seinan’s ace, Nishimura, delivers a perfect save with six consecutive strikeouts, securing Seinan’s spot in the semifinals.

The final game of the episode is between Meisei High and Saijo. Despite a shaky start by Meisei’s starting pitcher Natsuno, Meisei takes the lead thanks to home runs by Nangou, Koma, and Imagawa. Natsuno improves his performance from the second inning onward, and the ace Touma Tachibana closes out the ninth inning, securing Meisei’s victory.

The episode ends with anticipation for the semifinals, setting the stage for intense baseball action in the upcoming episodes. The characters express their determination to defeat their rivals and advance to the next phase of the championship.