A special episode of Stitch, taking place between season 1 and season 2.

Kayo Fujikawa has been acting strange recently, leading her clubmates Ayame Seki and Shiina Murakami to worry about her. Moreover, her birthday is just around the corner. To lighten the mood of their precious companion, Ayame and Shiina take it upon themselves to make sure that Kayo enjoys her special day. Set before the time Tamaki Honda joins the SNS club, this extra chapter of Stella no Mahou follows the club seniors as they develop their friendship.

Mayuri Shiina brings a cognitive computing system—with a large pink Oopa toy serving as its terminal—to the Future Gadget Lab, insisting that it will help her and Kurisu Makise prepare fried chicken for the group, much to the dismay of Rintarou Okabe and Itaru Daru Hashida. Despite not having the proper ingredients, the Oopa cognitive computer assists Mayuri and Kurisu in perfecting a dish that the other lab members will enjoy. In the following episodes, the cognitive computer continues to aid Okabe and his friends in their day-to-day lives. From helping Okabe and Kurisu to reconcile after an argument, to collecting input from the lab members to suggest improvements for the Lab; Okabe may not realize it yet, but his lab has gained a valuable asset!

The eccentric, self-proclaimed mad scientist Rintarou Okabe has become a shell of his former self. Depressed and traumatized after failing to rescue his friend Makise Kurisu, he has decided to forsake his mad scientist alter ego and live as an ordinary college student. Surrounded by friends who know little of his time travel experiences, Okabe spends his days trying to forget the horrors of his adventures alone. While working as a receptionist at a college technology forum, Okabe meets the short, spunky Maho Hiyajo, who later turns out to be the interpreter at the forum's presentation, conducted by Professor Alexis Leskinen. In front of a stunned crowd, Alexis and Maho unveil Amadeus—a revolutionary AI capable of storing a person's memories and creating a perfect simulation of that person complete with their personality and quirks. Meeting with Maho and Alexis after the presentation, Okabe learns that the two were Kurisu's colleagues in university, and that they have simulated her in Amadeus. Hired by Alexis to research the simulation's behavior, Okabe is given the chance to interact with the shadow of a long-lost dear friend. Dangerously tangled in the past, Okabe must face the harsh reality and carefully maneuver around the disastrous consequences that come with disturbing the natural flow of time.