Hatchan followed the map that he was given by the Macro Pirates to find the secret Takoyaki recipe. He followed the map and found the Octopus Mash. After a short fight, Octopus Mash was easily defeated, and Hatchan ran to save Keimi, angered since he thought the pirates lied to him.
After Hatchan beat Macro and his crew, he learned that there was a secret compartment in Octopus Mash's head. He returned and opened Octopus Mash's compartment, revealing the recipe and special Takoyaki sauce. Hatchan proceeded to take the defeated octopus and the sauce to make Takoyaki for his crush, Octopako.
Hatchan was later seen cooking the Takoyaki for the citizens of Headband Catfish Village instead of Octopako. It is unknown what happened to Octopus Mash afterwards.
It is unknown what happened to Octopus Mash in the end, but since he was seen unconscious with Hatchan and the sauce one second and the next Hatchan was making Takoyaki, an octopus dish, he could possibly have been killed and used in the meal. This has yet to be confirmed.