The Murder Case That Is Too Impossible

With the Dark Matter Thieves repelled, the heroes who fought are treated to a stay at a hot spring resort, only for Zombieman to be discovered sprawled dead on the floor. Child Emperor announces that the killer must be one of the S-Class attendees. The tale rewinds to the previous evening, when everyone bathed together and Metal Bat grumbled that idle names like Flashy Flash, Pig God, and Watchdog Man had been rewarded for handling unrelated cases rather than the invasion.

Sitch later assembles the group for a victory party, where a few heroes get drunk on sake to Child Emperor's distaste, and Zombieman quietly asks the boy whether he is enjoying the night.

Back at the crime scene, Child Emperor gathers clues and eliminates suspects one by one, fixing on the murder weapon: Atomic Samurai's katana. He grills several heroes, among them Saitama, who had earlier quizzed Zombieman about his immortality, and King, whose grim stare unnerves the investigator. Tatsumaki then storms in, threatening to bind everyone as suspects. When Zombieman revives, he recalls that the blade had hovered wrapped in a green glow much like Tatsumaki's flight, and Child Emperor begins to suspect she had been drunk.

She furiously denies it, insisting she knew the victim could not truly die, and Bang steps in to calm her before the gathering breaks up. Reviewing the night's surveillance footage at Sitch's request, Child Emperor sees plainly that a heavily intoxicated Tatsumaki was the offender.

Released on May 27, 2016, the episode caps its mystery with a joke about the true motive. Heading home, Saitama wonders aloud why Tatsumaki stabbed Zombieman, while Genos silently grasps the cause: Saitama had told her she was a child too young for adult sake, so the humiliated esper retaliated by draining as much of his bottle as she could.