Kaito Yashio and his friend Akiho Senomiya are the remaining members of their school's Robotics Club. After Akiho hands in a budget request to the staff room, both she and Kaito, who spends his time playing games on his PokeCon device, visit an old hangar containing a large robot the Robotics Club has been working on since its foundation, Gunvarrel, based on a popular robot anime whose final episode was never aired. The next day, the vice-principal agrees to give the Robotics Club their proposed budget on the condition that they win a robot tournament taking place in two week's time, with the club to be disbanded should they lose. As Kaito and Akiho contemplate if they can pull off such a feat, a mysterious girl is seen making a report.

As the robots continue to run rampant in Tokyo, Kona explains to Kaito that the login to their control panel has been altered by the hackers to require they defeat a Kill-Ballad CPU opponent. Struggling to beat the opponent, Kaito decides to try and force his slow-mo by pushing his body to its limits, but to no avail. Kona soon founds out the person behind the hack was one of the members from her development circle, Maguyan, who claims he was forced to do it as his family was taken hostage. Kaito soon realises that Maguyan has in fact been brainwashed. As Kona hears the support of her friends from the Robotics Club, she explains how she created Kill-Ballad to keep Gunvarrel, and her mother's memories, alive. As the police show at Kona's doorstep, Akiho, Junna and Subaru help lure them away, buying Kaito and Kona some time to beat the Kill-Ballad opponent.