One-Punch Man Episode 3: The Obsessive Scientist

The episode opens with a narration from Armored Gorilla recounting the backstory of Dr. Genus, a brilliant scientist disillusioned with humanity's stagnation, who founded the House of Evolution to forcibly advance human evolution through genetic experiments, creating animal-human hybrids and his own clones as subordinates. Impatient, Saitama demands a shorter version, learning that Genus wants his body for study; Genos proposes attacking the lab immediately, and Saitama agrees, though Genos's inquiry about cyborgs from four years ago yields no information from Armored Gorilla.

Saitama and Genos infiltrate the House of Evolution, where Dr. Genus and his clones panic over the intruders and activate traps and their ultimate creation, Carnage Kabuto—a massive, super-speedy, genetically enhanced beetle-human hybrid who enters a berserk "carnage mode" every Tuesday through Saturday. Kabuto tests Saitama with blinding speed but senses his danger and demands his strength's origin; Saitama reveals it came from three years of daily training—100 push-ups, 100 sit-ups, 100 squats, and 10 km running, without AC or heat, which also caused his baldness—leaving Kabuto, Genos, and Genus skeptical.

Enraged, Kabuto attacks Saitama viciously, threatening a town rampage if he wins, but Saitama realizes it's Saturday supermarket bargain day and ends the fight with a single punch, obliterating Kabuto. Dr. Genus, surviving due to immortal cells, witnesses Saitama's power and rethinks his views on evolution as Saitama and Genos rush out—Saitama punching a hole in the wall—barely making the sale in time.

Meanwhile, in a separate storyline, Silver Fang's top student Charanko learns from his master about Garou, a former student who was beaten and expelled; Genos speculates Garou's return motivated this. Walking home, Charanko overhears Garou confronting Mumen Rider, a licensed hero on a bike; Tank Top Vegetarian and his gang arrive, but Garou swiftly defeats them, struggling briefly against Tank Top Master until countering with Silver Fang's techniques. Silver Fang's brother Bang arrives to assist, but Garou dominates, smashing Mumen Rider's head into the ground with a counter to his Justice Crash, defeating Charanko and the gang, and preparing to target Class A heroes Golden Ball and Spring Mustachio.

The episode closes comically as Garou encounters the bald-headed Saitama on the street, assumes he's a hero, and chops him harmlessly; annoyed, Saitama retaliates with a casual chop, instantly knocking Garou unconscious.