Zombieman Murder Case 2

Child Emperor, Zombieman, Superalloy Darkshine, and Metal Bat are sent to a bleak, snow-covered mountain to hunt a monster. Turning up nothing, they check into a lodge for the night and find they are not alone: Saitama and Genos got stranded there too, and Flashy Flash is trying to unwind on vacation. Speed-o'-Sound Sonic is also training on the mountain, and once he senses Saitama, he decides to strike. Lingering too long in the blizzard, he freezes stiff, loses his footing, and smashes in through a window. The heroes tie him up, though he still intends to kill Saitama.

Sonic slips his bindings easily and tries to ambush Saitama from beneath the floorboards, only for Genos to intercept him, and their clash wrecks the room. The stirred-up dust tickles Saitama's nose, and his sneeze blasts every door and window in the lodge open. The power fails, and a sudden explosion follows.

Grabbing a flashlight, the heroes rush to the den to find it destroyed and Zombieman unconscious. Detecting no outside heat signatures, Child Emperor concludes the culprit must be inside the lodge. Once Zombieman recovers he shares what little he saw, and Sonic steps forward to clear his own name. With everyone's alibi checking out, and Flashy Flash upstairs forgotten entirely, they suspect the monster, but the association identifies it as a mere bear creature called Bruinado and rules it out. When Child Emperor watches Saitama sneeze a second time, he pieces it together: the lodge's many heaters dried the air, the Genos-Sonic brawl raised flammable dust, Saitama's sneeze drove that dust into the den, the strained electricity tripped a breaker, and Zombieman's lighter set off the explosion. Just as the group relaxes, Bruinado bursts through the front door and is instantly crushed by the crowd of S-Class heroes, while upstairs Flashy Flash keeps hogging all the power.

Four S-Class heroes hunting a monster get snowed in at a lodge shared with Saitama, Genos, and Flashy Flash. Sonic freezes outside and crashes in, and his fight with Genos plus Saitama's sneeze sets off an explosion that knocks out Zombieman. Child Emperor solves the chain of causes, and the bear monster Bruinado is destroyed the moment it finally appears.

This is the twelfth OVA in the anime series and part of the Season 2 supplementary lineup, following the entry titled Puri-Puri Prisoner and the Jailbreaking Prisoners. In one scene Saitama is shown reading Makai no Ossan, another work by the original creator ONE.