Starlight is a play loved throughout the world. Karen and Hikari make a promise with each other when they're young that one day they'll stand on that stage together. Time passes, and now the girls are 16 years old. Karen is very enthusiastic about the lessons she takes every day, holding her promise close to her heart. Hikari has transferred schools and is now away from Karen. But the cogs of fate turn, and the two are destined to meet again. The girls and other Stage Girls will compete in a mysterious audition process to gain acceptance into the revue.

Starlight is a play loved throughout the world. Karen and Hikari make a promise with each other when they're young that one day they'll stand on that stage together. Time passes, and now the girls are 16 years old. Karen is very enthusiastic about the lessons she takes every day, holding her promise close to her heart. Hikari has transferred schools and is now away from Karen. But the cogs of fate turn, and the two are destined to meet again. The girls and other Stage Girls will compete in a mysterious audition process to gain acceptance into the revue.

The stage emulates life and compresses it, setting free skills learned over lifetimes in brief but dazzling displays for the amusement and judgment of others. For the performers, it is the ultimate risk, and some will rise while others must fall. Nowhere is this truer than at the Seisho Music Academy, where music, dance and real weapons all come into play in the creation of the next great Star. Karen and Hikari’s destinies have been linked since a childhood promise, but their journeys here have taken very different paths. Now, after Hikari leaves, Karen must discover who she is without her opposite, while Hikari must rediscover her own course. Nor are they the only girls who must reassess and change if they want to achieve their dreams, as the dance, magic, and swordplay continue!

Ichika is a high school musician who can enter a mysterious place called “SEKAI,” where she and her friends express their innermost emotions through music alongside Hatsune Miku. One day after giving a live performance, Ichika meets a new Miku that she has never seen before. No matter how hard this new Miku tries to sing, she struggles connecting with the hearts of her listeners. Miku must rely on the help of others to find a way to sing again.

大场奈奈。
圣翔音乐学园第99期生 学号15号。
中学时代孤身一人身处演剧部的她，知晓了在这所学园首次创设舞台的真正喜悦。
以同一个舞台为目标，携手共进的99期生这些同志。
落幕的瞬间沸腾的掌声，以及令身体颤抖的充实。
让那如同燃烧宝石般的光辉
让那如同闪亮彩虹般的每个幸福之日，再一次——
被那份眩目囚禁的奈奈，参加了长颈鹿主办的谜之选拔。
成为合格者的她，期盼着在命运舞台上的「第99回圣翔祭，那一年间的再演」。
「好吧」
然后再次开始的，「那一年」。
奈奈将开花结果的才能，全部投入到那眩目之日的「再演」中。
但她尚未知晓。
没有完全相同的舞台。
没有不会结束的舞台。
在重复的再演前方，旋转的轮舞开幕。
「本该是演出过的舞台。但，却是我不知道的舞台」
「那就是，轮舞·轮舞·轮舞——我明白的」

Haga Ineko stopped being a school teacher for she was about to get married. When she is suddenly dumped by her to-be husband, she loses her way, and starts drinking. One day, an old friend approaches with a job offer. She would be a substitute teacher in a class on which several teachers gave up without an apparent reason. She reluctantly takes the job only to discover that there are several brutal bullying cases inside the class. Even she eventually starts being anonymously threatened due to her opposing posture against such cases. She now has to identify and reprimand them while at the same time protecting weaker students. The word "Hagane" on the title is a nickname which comes from Haga (her surname) and Ne (from Ineko, her name), but is actually a pun with the actual word hagane (which means steel, denoting how she must be in order to resist as a teacher). (d-addicts.com)

分别收录于三卷BD中的特典动画。第一集名为《99.419 採寸》，收录于BD第一卷，2018-10-24发售；第二集名为《99.419 討論》，收录于BD第二卷，2018-12-26发售；第三集名为《99.419 開演》，收录于BD第三卷，2019-02-27发售。

分别收录于三卷BD中的特典动画。第一集名为《99.419 採寸》，收录于BD第一卷，2018-10-24发售；第二集名为《99.419 討論》，收录于BD第二卷，2018-12-26发售；第三集名为《99.419 開演》，收录于BD第三卷，2019-02-27发售。

Rinku se muda a Japón y se inscribe en la Academia Yoba, donde ser DJ es tendencia. Fascinada tras ver un concierto, decide formar su propia unidad con Maho, Muni y Rei. Juntas competirán con grupos como Peaky P-key y Photon Maiden mientras persiguen el éxito.