For Koutarou Murata, an overworked salaryman, his local ballpark is the only place where he can truly unwind from his arduous daily life. One evening, he is approached by Ruriko, the new lively beer vendor, trying to sell her first drink to him. Koutarou accepts Ruriko's offer, marking the start of their friendship and lots of playful teasing. While Koutarou tries to enjoy baseball to the fullest and Ruriko diligently seeks for more customers, many fans with heartwarming stories of their own come to fill the ballpark and enjoy the space that brings them all together.

The dying planet of Eltria is the only home of Kyrie Florian, her older sister Amitie, and her parents, who are scientists researching ways to save it. Unfortunately, the Florians must leave the planet behind to seek medical care for their father, who has contracted a lethal illness. Even with treatment, the survival rate of Kyrie's father is minuscule. Refusing to give up on her father and Eltria, Kyrie goes against the wishes of her sister and runs away from home to the peaceful planet of Earth in search of a solution. There, Kyrie and her childhood friend, Iris, pursue Earth's magical protectors—Nanoha Takamachi, Fate Testarossa, and Hayate Yagami. Nanoha and her companions possess the key to fulfilling Kyrie's objective, and the young girl must do whatever it takes to obtain it. However, it proves difficult for Kyrie, as the protectors do not easily yield to her provocation. Furthermore, Amitie soon arrives on Earth to stop her younger sister's reckless actions and bring her back home, further complicating the already delicate situation.

IDOLiSH7 is more successful than ever, but no one is smiling because a new threat has taken the stage: the debuting idol group ŹOOĻ. Managed by the nefarious entertainment executive Ryou Tsukumo, they will stop at nothing to get their way, resorting to all kinds of underhanded tactics to bring down their rivals. TRIGGER's image has already been ruined by scandal, and IDOLiSH7 and Re:vale are headed for the same fate—or worse. Meanwhile, Zero, the legendary idol who disappeared 15 years ago, continues to haunt the present through those he left behind. His manager seems to be in contact with Tsukumo for his own schemes, and Zero's songwriter reveals himself in a letter after having been missing for years. IDOLiSH7 finds an ally in Re:vale to thwart ŹOOĻ's plans while trying to make sense of Zero's colleagues' actions, but it may be impossible for everyone to emerge unscathed.

The fourth film in the six-part Girls & Panzer: Saishuushou film series.