Stinger vs. Seafolk

Stinger vs. Seafolk was the battle between the A-Class hero Stinger and the Seafolk that invaded J-City.

Prelude
An octopus-like Seafolk appears on the surface of the Earth, claiming their kind will take over the surface before it is killed by Saitama. Later, its fellow Seafolk appear from the ocean and cause havoc in J-City. One of them grabs a citizen with its tentacle, threatening all that stand in its way. However, the monster's tentacle is cut by the A-Class rank 11 hero Stinger, and he saves the citizen. The hero introduces himself to the crowd of fans and monsters as he challenges them to a fight.

Battle
The scene later fast forwards to a wounded Stinger facing down four Seafolk after killing six of them. He is shown to have blood running down his face and a large bruise as well, breathing heavily while facing the remaining Seafolk. Stinger admits to the monsters that they have spunk, yet calls them slimy bastards. He goes on by saying his bamboo shoot is stoked to battle enemies with some power for a change, yet he claims that it is time to end this. One of the Seafolk tells the hero to quit his boasting, remarking that his ridiculous fan club had already left. Another Seafolk assures Stinger that his death will be painful, and that Stinger will suffer for the deaths of their brothers. However, Stinger is undeterred and actually states that not having an audience around makes it easy for him. One of the Seafolk attacks Stinger with its tentacle, but Stinger unleashes his technique Gigantic Drill Stinger, followed by Quadruple Thrust, to kill the final Seafolk and claims victory.

Aftermath
While Stinger celebrates his victory, thinking he stopped a God-level threat, Deep Sea King appears and defeats him in one punch, although this was while he was significantly injured and off-guard. At some point after his defeat, he was promoted to A-Class rank 10. His defeat resulted in the threat level of the Seafolk invasion being raised to Demon.