Aspiring Orange Company Undine Anya Dostoyevskaya feels dejected upon learning that her gondolier mentor, Alice Carroll, is not spending much time with her own mentor, Athena Glory. Athena—the Undine-turned-opera singer—has been attempting to arrange a meeting with Alice, but the latter seems to be avoiding her for unknown reasons. To try and resolve this predicament, Anya calls upon her fellow Undines Ai Aino and Azusa B. McLaren. As the trio works to bring Alice and Athena together, Anya gains a deeper insight into her seniors' feelings, which might just be the key to untangling the uncertainties between them. [Written by MAL Rewrite]

Aria the Crepuscolo was released to celebrate the 15th anniversary of the Aria the Animation anime adaptation. The movie features an original story written by series creator Kozue Amano. The film was released on Blu-ray in Japan on August 18, 2021.