In the futuristic city of San Fransokyo, Hiro Hamada, a 14-year-old high school graduate and robotics prodigy, spends his time competing in illegal underground robot fights. Hoping to get him out of this dangerous lifestyle, his inventive older brother Tadashi takes him to the San Fransokyo Institute of Technology, where Hiro meets Tadashi's four best friends – gritty Go Go Tomago, neurotic Wasabi, bubbly Honey Lemon and comic book fan Fred. Tadashi also introduces his project, inflatable healthcare robot Baymax. After meeting Tadashi's mentor Professor Robert Callaghan, Hiro applies to the university, but when the celebration is brief as a fire breaks out while Callaghan is still in the building. Tadashi rushes back inside to save him, only for the building to explode, with both declared dead. Two weeks later, Hiro inadvertently activates Baymax. Hiro's only remaining microbot begins to move on its own, so he and Baymax follow it to an abandoned warehouse. Inside, they discover the microbots being mass-produced by a Kabuki mask-wearing supervillain known as "Yokai", who tries to dispose of Hiro and Baymax, Deducing that Yokai was the mastermind behind the fire, Hiro weaponizes Baymax for defense, and Hiro's friends, whom Baymax contacted, meet up with them. Yokai pursues the group through the streets, but Baymax saves them. So They Have To Work Together To Defeat Yokai Or Whoever Is Doing This.
