The film's story begins when Arata inadvertently touches "Hermes Apocrypha," Lilith's Grimoire. Suddenly, he is enveloped by a bright white light, and a girl appears before him. She calls herself Lilim, and treats both Arata and Lilith as her parents. At the same time she appears, something changes in the world. The forbidden Eternal Library awakens. In the Library is sealed the ultimate culmination of Alchemy, the White Demon Lord. The White Demon Lord plots to eliminate Arata and the Trinity Seven to usurp the position of Demon Lord. Bristling with untold power, the White Demon Lord attacks Arata, and triggers a desperate crisis where Arata and the Trinity Seven must save the world in this last battle.

The Academy City on the water, Rikka (also known as Asterisk) is the world's largest stage for the integrated battle entertainment, "Star Wars Festival." The young boys and girls of the "Starpulse Generation" belonging to the six academies made their wishes with Shining Armaments in their hands, vying for supremacy-Amagiri Ayato is one of them.

Mizore Yoroizuka and Nozomi Kasaki are two close friends who are part of the Kitauji High School music club. Quiet and reserved Yoroizuka plays the oboe while lively and popular Kasaki plays the flute. The group has decided to play Liz and the Blue Bird, a song inspired on a fairy tale about the relationship between a girl and a bird. The musical piece puts both Mizore and Nozomi on the spotlight due to a solo part by Yoroizuka and forces the two girls to reexamine their friendship.

Based on Vocaloid songs from "Kokuhaku Jikko Iinkai ~Renai Series~" by HoneyWorks, the movie is the second film based on the songs, following Tetsuya Yanagisawa's previous anime, "I Want to Let You Know That I Love You".