Alongside Genos, his faithful disciple, Saitama performs his official hero duties as a member of the Hero Association. One day, monsters claiming to be from the Monster Association suddenly appeared, taking a child of the Hero Association executive hostage. The S-class heroes gather and plan a raid on the Monster Association hideout to rescue the hostage. Meanwhile, Garou, a “human monster” who was taken by the Monster Association during a battle with the heroes, awakens in the Monster Association hideout.
The heroes plan a rescue of a child kidnapped by monsters, while Garou awakens deep underground.
On his way to hunt heroes, Garou dines and dashes at a restaurant, but is chased by Saitama.
Garou fights Insect God and King the Ripper, while Tareo gets kidnapped. Dr. Kuseno visits Saitama.
The heroes prepare for battle without Silverfang and Genos. Garou attacks the Monster Association.
Garou rescues Tareo but is struck by Overgrown Pochi, falling to Orochi and Gyoro-Gyoro.
Class-S heroes plan the Monster Association assault, but Amai Mask arrives and clashes with them.
Heroes arrive in Z City but face a monster ambush. A-class aids while Gyoro-Gyoro watches the fight.
Tempest Wind and Hellfire Flame, who were ninjas but are now monsters, battle with Flashy Flash.
Child Emperor finds Waganma and faces Phoenix Man, using his ultimate weapon to protect him.
Zombieman faces Vampire, a descendant of a supernatural bloodline, in a brutal, deadly showdown.
Child Emperor rescues Waganma. The heroes take on threat-level Dragon monsters in a deadly fight.
The heroes battle monsters while Terrible Tornado faces Gyoro-Gyoro. Orochi appears before Saitama.
