Kanae Ito

On the day Tōma Kamijō and Index see Academy City's space elevator, Endymion in the distance, they meet a Level 0 girl with an amazing singing voice, Arisa Meigo. As the three enjoy their time together after school, magic-user Stiyl Magnus suddenly attacks them. His target: Arisa. Why would a girl from the science side be targeted by someone from the magic side, Tōma wonders. In the chaos of Stiyl's attack, he tells Tōma, Index and Arisa that she might cause a war between the magic side and the science side.

Kirito and some of his new friends look back at the events of season one. Kirito recalls his defining moments while Suguha learns to swim with the help of Asuna and other girls who fought alongside Kirito.

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...

The film centers on Asuna, a young girl who spends her solitary days listening to the mysterious music emanating from the crystal radio she received from her late father as a memento. One day while walking home she is attacked by a fearsome monster and saved mysterious boy named Shun. However, Shun disappears and Asuna embarks on a journey of adventure to the land of Agartha with her teacher Mr. Morisaki to meet a Shun again. Through her journey she comes to know the cruelty and beauty of the world, as well as loss.

Abandoned after coming out, Shun befriends Mio just before he has to move. Years later, Mio returns with a confession. How will Shun feel?