Upon returning from their class trip, E Class are greeted by their first transfer student, an AI-powered machine from Norway known as the Autonomous Intelligence Fixed Artillery, who uses calculations to adjust the accuracy of her attacks. However, the class quickly gets sick of her constantly firing her weapons during class, deciding to tape them shut themselves so they can study properly. Wanting the AI to get along better with her classmates, Koro-sensei makes some modifications to her hardware and programming, giving her a more human personality that her classmates, who nickname her "Ritsu", come to appreciate a lot more. Later that night, Ritsu's creators, who are less than happy with the changes, decide to remove all the modifications that Koro-sensei made and forbid any further changes or tampering. However, Ritsu manages to hide her new personality from them before it is deleted, deciding to secretly defy her creators for the sake of keeping her promise to help her classmates.