Fifty years ago, mysterious creatures known as the Huge suddenly appeared all over the world, posing an existential threat to humanity. To defend against these menaces, soldiers in the form of teenage girls known as Lilies use the energy Magie within their bodies to power weapons called Counter Huge ARMS or CHARMS. After being saved by a Lily two years ago while evacuating from a Huge attack, Riri Hitotsuyanagi vowed to become a Lily herself. She enrolls in the prestigious academy of Yurigaoka, a training ground for Lilies, and discovers that one of her classmates is Yuyu Shirai—the same Lily who rescued her. Much to her confusion, however, the person she thought to be cheerful turns out to be quite antisocial and prefers to fight alone. Even so, Riri still desires to get along with Yuyu and is willing to do anything she can to reach that goal. With Yuyu and the other Lilies by her side, Riri's journey on becoming one of them has just bloomed!

Kasumi Toyama and the members of Poppin'Party—their high school band—are now second-year students, but with the new school year comes their latest set of challenges: student council duties, cram school, and part-time jobs, among other things. Furthermore, they are now separated into different classes, and as a result, their free time together is shortened. Looking back, their joyful times together seem like nothing more than an unachievable fantasy when their members are too occupied to even gather in Arisa Ichigaya's basement for practice sessions. As the band ponders over the situation, an unfamiliar girl suddenly emerges, unknowingly pulling them into the spotlight once more. In this rising era of girl bands, Afterglow, Pastel*Palettes, Roselia, and Hello, Happy World! begin to make their appearance as well. Each band, comprised of musicians with their unique personalities, illuminates the stage with its performances. As Poppin'Party returns to the music scene and encounters new friends, the sparkling, heart-pounding music starts to play once again!

When Kasumi Toyama was out camping as a child, she heard the rhythm of the Star Beat while admiring the starry night sky. This sparkling, heart-pounding sound left a lasting impression on her, and since then, she has constantly been seeking to rediscover that exciting thrill. Now, as a newly enrolled student of Hanasakigawa Girls' High School, Kasumi is more determined than ever to find that long-lost sensation again. She attempts a myriad of school club activities, and even considers taking up a part-time job, but none of these feel suitable for her. That is, until she chances upon a star-shaped guitar in the storage room of an old pawn shop. It leads her to a live house, where she is captivated by watching a live performance for the first time. Spurred from the adrenaline, she instantly decides to form a band without even really knowing why. However, such a venture requires her to confront various hurdles with new friends she makes along the way, all in her pursuit to encounter that twinkling, heart-throbbing ardor once more.