Donyatsu is a chocolate-coated, donut-shaped creature with feline traits. He awakens in a desolate, humanless Shinjuku, Tokyo, surrounded by human skeletons, possessing no memory of his origins, identity, or personal history, including his own name. His existence unfolds in a post-apocalyptic landscape devoid of humans, the result of an unexplained catastrophe. Abandoned infrastructure and a non-functional mecha indicate recent devastation. Donyatsu explores this ruined environment alongside similarly food-themed companions like the bagel cat Begaru and the character Ronya. Their days are filled with playful explorations and interactions within the urban decay, engaging in casual conversations, word chain games, and hero roleplay. These activities occur amidst subtle clues about the world's collapse, including discarded technology and environmental decay. A background conflict simmers between cat and mouse factions, though Donyatsu's specific role is unclear. His narrative centers on observing and adapting to the surreal, often darkly humorous reality of a world reclaimed by bizarre food-animal hybrids. The juxtaposition of his whimsical design against the bleak setting blends lighthearted adventure with underlying science fiction mystery. Within available storylines, he exhibits no significant personal evolution or resolution to his amnesia.