Tightly clutching his Gibson guitar, Mafuyu Satou steps out of his dark apartment to begin another day of his high school life. While taking a nap in a quiet spot on the gymnasium staircase, he has a chance encounter with fellow student Ritsuka Uenoyama, who berates him for letting his guitar's strings rust and break. Noticing Uenoyama's knowledge of the instrument, Satou pleads for him to fix it and to teach him how to play. Uenoyama eventually agrees and invites him to sit in on a jam session with his two band mates: bassist Haruki Nakayama and drummer Akihiko Kaji. Satou's voice is strikingly beautiful, filling Uenoyama with the determination to make Satou the lead singer of the band. Though reticent at first, Satou takes the offer after an emotional meeting with an old friend. With the support of his new friends, Satou must not only learn how to play guitar, but also come to terms with the mysterious circumstances that led him to be its owner.

High school student Haru Yoshioka is bored with the monotony of life. One day, she saves Prince Lune of the Cat Kingdom from being run over by a truck. As a token of gratitude, the Cat King sends her "presents" and invites her to the Cat Kingdom to become Lune's wife. Haru's inability to properly communicate with the cats leads to the misunderstanding that she has accepted the proposal.

As Haru ponders on ways to escape the predicament, a mysterious voice instructs her to search for the Cat Bureau. However, not long after she finally arrives at the bureau, a horde of cats swarms in and forcibly takes her to the Cat Kingdom, along with a member of the Cat Bureau. Concerned for their safety, owner of the Cat Bureau, Baron Humbert von Gikkingen, follows close behind.

The more Haru immerses herself in the activities of the Cat Kingdom, the more cat-like she becomes. To her dismay, she soon learns that, unless she can find her true self, she may become a cat permanently. Haru's adventures in the world of cats lead her down a path to self-discovery, allowing her to return as a more confident person.

In 2026, four years after the infamous Sword Art Online incident, a revolutionary new form of technology has emerged: the Augma, a device that utilizes an Augmented Reality system. Unlike the Virtual Reality of the NerveGear and the Amusphere, it is perfectly safe and allows players to use it while they are conscious, creating an instant hit on the market. The most popular application for the Augma is the game Ordinal Scale, which immerses players in a fantasy role-playing game with player rankings and rewards.

Following the new craze, Kirito's friends dive into the game, and despite his reservations about the system, Kirito eventually joins them. While at first it appears to be just fun and games, they soon find out that the game is not all that it seems...

[Written by MAL Rewrite]

This is a remix, theatrical release of the first half of the Appleseed XIII series.