With the ensemble contest behind them, the members of the Kitauji High School concert band now aim to win a gold medal at the national competition. For third-year club president Kumiko Oumae and her friends, it is their last chance before graduation. Filled with anticipation and anxiety, Kumiko worries if she can successfully lead the band. Amid her struggles, Kumiko encounters transfer student Mayu Kuroe. From her gentle demeanor to her talented euphonium skills, Mayu was a member of the Seira Girls' School concert band—a regular at nationals. While Mayu is friendly, Kumiko cannot help but have an indescribable feeling from their meeting. As new members arrive and plans are set in motion, the club, with an insatiable hunger for a gold medal, learns what it truly takes to propel themselves to reach the national level.

Haruka Kiyomine and Kei Kaname were once recognized as the most formidable pitcher-catcher duo in middle school baseball. Known as the "General," Kaname paired his expert strategies with Kiyomine's explosive pitches, crushing the dreams of many starry-eyed players who hoped to one day make it to the big leagues. High school freshman Tarou Yamada is one such former player. Having given up on competing, he enrolls in Kotesashi High School—a completely average public school with no baseball team to speak of—where he discovers that his new classmates are the legendary pair who once destroyed his dreams. Adding to this shocking revelation, he learns that amnesia has reduced the once level-headed General to a vulgar class clown. Having lost all interest in baseball, Kaname dragged a disappointed Kiyomine to Kotesashi simply because the school was close to where they live. As Kotesashi forms a fledgling baseball club, Yamada meets other players he once admired who also left baseball behind. While they might be unwilling now, Yamada believes that if he can convince such talented athletes to start playing again, it might be possible to achieve their dreams and win the national championship—as long as they can put up with Kaname's incessant joking.

Featuring stories from the manga not adapted in the main anime.

In a dark corner of the universe, intergalactic criminal Kain breaks out of prison and destroys the Galaxy Police Headquarters. Basking in the afterglow of the terror and destruction he has caused, Kain sets his sights toward a much bigger prize waiting on Earth. Meanwhile, Tenchi Masaki and his crew are watching some old home videos of his mother, Achika. As the film rolls, Achika slowly starts to vanish. While watching her fade away, Tenchi also begins to disappear. However, thanks to a device created by Washuu Hakubi, Tenchi is not gone for good. The gang soon learns about Kain and deduce that he must have done something to Achika, which has resulted in time being altered. To save himself and maintain the future, Tenchi travels with the girls back in time to protect his mother from her fate.