"The Man Who Wants To Be A Monster" (怪人になりたい男, Kaijin ni Naritai Otoko) is the 40th chapter of the One-Punch Man manga series.
Garou is excitingly yelling at the other criminals to fight, since it's the only reason he came, to see who is the strongest. Sitch rejected such an idea and tells Garou to leave the facility. Garou later changes his mind and decided to conduct evil. Sitch advises his bodyguards to deal with him to which they agree.
Garou then reminiscence his days as a child, where he watched a show about Justice Man and was rooting for the villains. He later found out that justice always prevails and decided he will become the strongest monster ever to change that scenario, while choking Magic Trick Man.
Heavy Tank Loincloth attacks Garou in an attempt to save Magic Trick Man, but Garou manages to break his arm and knocks him out with a single punch. The criminals cheer on Garou, only for him to state they will die too. As the criminals defend themselves, stating they are not on the heroes side, Garou simply replies he is neither on the heroes nor human side, instead on the monsters side. Blue Fire agrees with that statement and tries to burn Garou with one of his attack only for Garou to rip off his arm. While Sitch calls for backup, the criminals attack Garou.
Outside, Sonic is leaving the Hero Association Headquarters. He heard commotion coming from the headquarters, but simply brushes it off, since he already wasted his time, for not finding Saitama and declaring he will one day defeat him. In the mean time Saitama is playing a game with King, who complains of always losing.
At the headquarters, Garou managed to beat every single criminal and declared a war against the heroes. He declares in half a year, he will become stronger and challenge King, the strongest man on earth, leaving Sitch covering in the corner.