"Show By Rock!! Short!!" is a spin-off of the original "Show By Rock!!" series, condensing its vibrant musical and comedic elements into bite-sized episodes. The story is set in the whimsical world of Midi City, where anthropomorphic animals and other fantastical beings form bands and compete in music battles. The narrative primarily revolves around Cyan, a shy cat girl who is transported to this world after encountering a mysterious portal. She joins the band Plasmagica, consisting of the energetic rabbit Chuchu, the cool and collected sheep Retoree, and the mischievous alien Moa. Together, they navigate the challenges of the music industry while forming bonds of friendship.

The series maintains a lighthearted tone, focusing on the daily lives and humorous interactions of the band members and other characters from the "Show By Rock!!" universe. Episodes often highlight the quirky personalities of the cast, such as Chuchu’s over-the-top enthusiasm, Retoree’s calm demeanor, and Moa’s playful antics. Other bands, such as ShinganCrimsonZ and Criticrista, also make appearances, adding variety to the comedic and musical dynamics. The plot is episodic, with each short episode presenting a self-contained story that often revolves around practice sessions, performances, or comedic misunderstandings.

While the series does not delve deeply into overarching plotlines, it emphasizes the themes of teamwork, self-expression, and the joy of music. The characters’ growth is subtly portrayed through their interactions and shared experiences, reinforcing the importance of collaboration and perseverance. The humor is often derived from the exaggerated personalities of the characters and the absurd situations they find themselves in, making it an entertaining watch for fans of the original series and newcomers alike. The musical performances, though brief, remain a core element, showcasing the vibrant energy and creativity of the bands. Overall, "Show By Rock!! Short!!" serves as a charming and accessible extension of the "Show By Rock!!" universe, offering a quick and enjoyable dive into its colorful world.