The continent of Atlatan once again finds itself devoured by the flames of war after a horrific event known as the Great Hall Tragedy. What was supposed to be a joyful occasion that would establish peace between the Fantasia Union and the Factory Alliance, the marriage of Sir Alexis Douse and Lady Marrine Kreische, was instead a tragedy. As the bride and groom walked down the aisle, the ceremony was suddenly interrupted by a powerful convergence of "Chaos," a dark energy from another dimension that corrupts the land and brings forth monsters and demons into the world. From within that energy appeared the Demon Lord of Diabolos, an evil being who instantly murdered the archdukes of both factions, shattering any hope for peace between them. Having failed to prevent this disaster, Siluca Meletes, an Alliance mage, is traveling through the Chaos-infested countryside to study under a master magician. When she is intercepted by a group of soldiers working with the Federation, Siluca is rescued by Theo Cornaro, a young warrior carrying a mysterious "Crest," a magical symbol that gives its wielder the ability to banish Chaos. Bearing no allegiance to a specific domain, Theo hopes to attain the rank of Lord so that he can liberate his home town of Sistina from its tyrannical ruler and the Chaos spreading within it. Impressed by his noble goal, Siluca enters into a magical contract with Theo, and the two embark on a journey to restore balance to their war-torn land. [Written by MAL Rewrite]

During the school's spring break, Kyouya "Kyoro" Shinomiya has once again been kidnapped. Upon release, he finds himself in the GJ Club room, together with his captors, the cute GJ club members. At first glance, Kyoro does not see anything out of the ordinary in the club room, but as he gazes out of the window, he realizes that they are no longer in Japan but in New York!

The band "given"—comprised of Ritsuka Uenoyama, Mafuyu Satou, Haruki Nakayama, and Akihiko Kaji—has advanced to the final screening of the Countdown-fes Amateur Contest, in which they will be judged on their live act. Although enthusiastic, they worry about having only one original song to perform.

Mafuyu embraces the idea of learning more about music in order to create new, emotionally resonant songs. In this regard, he unexpectedly receives help from Ugetsu Murata, Akihiko's on-again, off-again lover. Ugetsu has unsuccessfully tried to let go of Akihiko, who himself is torn between lingering feelings for his past and an uncertain resolve for the future.

As the competition draws near, Haruki uncharacteristically begins to doubt his place in the band and the trust he shares with Akihiko. It is a given that not all attachments last forever, but it remains to be seen what can be salvaged from the ruins of heartbreak—or if only regrets will endure.

[Written by MAL Rewrite]

Based on the Fate/Kaleid Liner Prisma☆Illya 2wei! manga by Hiroshi Hiroyama, which is a spin-off of the Fate/stay night erotic visual novel by Type-Moon.