A year had passed since «My Hero Online» (MHO) was cleared. Izuku Midoriya (Deku) and Tenya Iida (Ingenium) were asked by government official Taneo Tokuda to investigate a game called Cybertronian Online, specifically a player who called himself «Laser Blade» and possessed a weapon that seemed to link deaths in the virtual reality (VR) world to those in the real world. Not only did Izuku find out that the criminal was associated with the Red Guild, The League of Villains, from MHO, but based upon how he killed his victims, Tenya linked it to a criminal in the real world who nearly killed his older brother while he was on patrol on the streets as a cop. To put an end to L.O.V.'s killing spree once and for all, and to get revenge for his brother, Deku and Ingenium entered the Cybertronian Online tournament, to only make contact with the player Laser Blade, but to put to the sins they committed in My Hero Online behind them once and for all.

Izuku Midoriya(Deku) and some of his new friends look back at the events of the last story. Deku recalls his defining moments while Ochaco Uraraka (Uravity) and the rest of their friends who'd fought alongside him to enjoy their time at the beach while helping teaching their friend to swim.

Virtual reality has advanced significantly by the year 2022, and My Hero Online (MHO), a sizable online role-playing game, is released. Players can direct their avatars in the game using only their thoughts thanks to "NerveGear" technology. Izuku Midoriya, often known as "Deku," is a 14-year-old boy who endured relentless bullying and jeers from his peers for having low self-esteem, particularly from his boyhood friend Katsuki Bakugo. His mother, feeling sorry for him, bought him a Nervegear and the MHO beta to help him gain confidence. He was one of the fortunate few gamers who received the initial shipment of the game upon the launch of the official service. He logs on and discovers himself, along with 10,000 others, in the beautiful and intricate Musutafu world, which is full of Super-Heroes, Super-Villains, and strong quirks/powers. The gamers quickly come to the painful realization that they cannot log out since the game's designer has imprisoned them in his new universe. Deku will now need to communicate and work with his fellow players to escape Musutafu. Some of them are comrades, while others are enemies, such as Ochaco Uraraka, a.k.a. Uravity, who is in charge of the main group trying to flee the brutal game. Even worse, My Hero Online is not just for entertainment purposes; if a character dies in Musutafu, they also perish in real life. Deku must adjust to his new environment, battle for his life, and attempt to escape his virtual prison.