Episode 24

Bang trades his Water Stream Rock Smashing Fist with Garou, and Genos observes that the master's command of the style dwarfs the student's, treating the outcome as settled. Bang fights with unprecedented ferocity, slamming Garou down and forcing him to fear his own death, but Garou escapes using the borrowed movements of Watchdog Man. When he reaches for Death Gatling's body as a shield, Bomb kicks him aside. Phoenix Man, watching from above, understands that returning to Orochi requires Garou to survive, so he descends, scatters the heroes with gusts from his wings, and carries the hunter off. As Genos moves to shoot them down, Phoenix Man summons Elder Centipede, whose eruption from the earth blocks the cannon and nearly drops the heroes into a widening chasm. Phoenix Man notes that Gyoro Gyoro reckons only Tatsumaki, Metal Knight, King, and Blast could hope to fell the creature.

Genos scorches its face while Bang and Bomb combine into the Whirlwind Water Stream Roaring Aura Sky Ripping Fist, driving the monster back, yet its cracked shell simply regrows a fresh face and greater power. Fearing civilian deaths, Genos throws himself at Elder Centipede despite the elders' protests and Dr. Kuseno's warnings, slashing at its eyes before being bitten, sliced in half, and swallowed whole. From inside he unleashes his Ultra Spiral Incineration Cannon and is spat back out, but the shell fuses again and disperses the heat. As Bang strips off his shirt to make a suicidal last stand, King strides in with a megaphone, claims he has brought Blast, and goads the vengeful centipede toward his position to spare the city. When the creature charges, King calls out and Saitama arrives just in time, ending Elder Centipede with a single Serious Punch that disintegrates it. Afterward Saitama admits the punch cured his frustration over losing to King, and when a battered Genos asks what he lacks, Saitama offhandedly answers power, sending the grateful cyborg into fresh resolve as they head home.

Bang decisively outclasses Garou before Phoenix Man rescues him and calls forth the Dragon-level Elder Centipede. Genos, Bang, and Bomb cannot overcome the monster's regenerating shell despite Genos's internal incineration attack. King lures the creature with a bluff about Blast, and Saitama destroys Elder Centipede with one Serious Punch, closing the season.

Carrying the title The Wiping of the Disciple's Butt, this Monster Association Arc episode is season two's twelfth and final installment, adapting chapters 83 through 85. It aired in Japan on July 2, 2019, and in English on January 11, 2020, with Seijaku no Apostle serving as the ending theme. Among the adaptation's tweaks, Garou lands on already-slain monsters rather than being thrown onto living ones, and Genos steadies Bang and Bomb after Elder Centipede knocks them back, a save absent from the manga.