In the animated short Detective Pikachu & the Mystery of the Missing Flan, Gonbe is the Japanese name for the character more widely known as Munchlax. He appears as a friend and assistant to Detective Pikachu, who has employed him to help film a video of his morning routine, a popular trend on the internet.

Gonbe's personality is not explored in great depth within this short, but his actions reveal a mischievous and food-obsessed nature. When Tim Goodman remarks that Gonbe looks like a Pokémon who eats a lot, the comment immediately exposes one of his hidden snacks, a banana, which falls out from his fur. This suggests a secretive and slightly guilty demeanor regarding his foraging. Upon being caught with the banana, Gonbe's primary motivation becomes clear: fear of getting in trouble, causing him to run away. His main drive throughout the story appears to be related to finding and consuming food, though he is honest enough to admit to taking the banana when confronted, while denying any knowledge of the missing flan.

Gonbe's role in the story is initially that of a red herring and a source of comic relief. He is the first suspect Tim accuses after Pikachu, due to his reputation for eating large amounts of food. His chaotic escape, which involves slipping on a skateboard and being thrown onto a ceiling fan, causes a cascade of stolen food items to fall from his fur, further cementing his role as a playful thief. However, by the end of the short, his role shifts. After the true culprit, an Applin, is caught, Gonbe eats the recovered banana and suddenly seems to remember something important. This memory turns him into a new client for Detective Pikachu, setting up further adventures.

In terms of key relationships, Gonbe is clearly on good terms with Detective Pikachu, who refers to him as a friend and trusts him to help with the video shoot. In contrast, his relationship with Tim Goodman is more antagonistic, as Tim immediately suspects him of eating the flan and accuses him of being a big eater, which puts Gonbe on the defensive and prompts him to flee. Gonbe's most notable ability, showcased during his escape, is his capacity to hide a surprisingly large amount of food within his fur. The banana is the first to fall out, but as he spins on the ceiling fan, a veritable collection of food items is revealed, demonstrating this unique and comedic talent.