Absurdist writing is used to explore deep themes like human nature and existentialism in unconventional ways. While there are other ways of doing so, anime and manga that have delved into the absurd often use surrealism and comedy to tell their story. Some of the most prominent examples of this are Gurren Lagann using mecha anime tropes to discuss the theory of overpopulation and Serial Experiments: Lain tackling the self and the internet in a way that's more relevant today than when it was created.
Rust-Eater Bisco is the newest absurdist anime, its theme gradually coming to light with each new episode. In a Japan ravaged by a mysterious explosion that brought about the Rusting, a painful disease that looks and behaves like rust on a machine, survival is the priority. Nekoyanagi Milo is a city doctor who is searching for a cure to save his sister, Pawoo, from the Rusting. He finds a companion in Akaboshi Bisco, who's wanted for acts of terrorism. Bisco takes an interest in Milo because they share a goal -- finding a cure to the Rusting -- and are both working toward it in their own way. Though, the method for creating the cure is also why Bisco is a wanted man. With this setup, Rust-Eater Bisco wants to discuss pandemics and how different people react in such a situation.
Rusting is a disease fitting the description of a pandemic. How it spreads remains unknown as of Episode 3, but precautions are still being taken. People in gas masks patrol the city and spray something as they go through sparsely populated streets. Milo tells Rusting patients to avoid leaving the city if at all possible. Street vendors tout miracle remedies while the governor insists that a cure only exists for the wealthy. Pawoo has stopped going to work and spends her days in her room with only a television to entertain her. These actions follow common guidelines from several past pandemics: stay inside, avoid large gatherings and disinfect as often as possible.
While enforcing these restrictions, the government also appears to be fighting the cause of Rusting. Throughout the first two episodes of Rust-Eater Bisco, the audience is led to believe the same thing many characters in the show do: that mushrooms somehow relate to its spread. Possessing mushrooms is illegal and dealing of them is done on the streets. Mushroom Keepers, who can grow the fungi anywhere, are called terrorists because of the belief that Rusting appears where mushrooms spawn.
However, Bisco contradicts this in Episode 3 when he claims that mushrooms aren't the cause, but rather the cure. According to him, Mushroom Keepers travel and plant their mushrooms in places ridden with Rusting because they've evolved to feed off of it. Thus far, the only person besides a fellow Keeper to believe him is Milo, who has been secretly buying mushrooms and trying to create a cure. He sees the correlation between the fungi and rust as a potential solution, but most others don't.
People in such an uncertain situation as a pandemic are often driven by fear and survival instincts. What was once normal has been altered because of the disease and very few aspects of their lives feel stable. Pawoo is the head of the city patrol but her case of Rusting prevents her from doing her job. All she has to look forward to is Milo returning home with food, if she can stomach it. She is directly affected by this disease and wants to be cured, but still doesn't believe Bisco's version of events. What she sees is the chaos caused by Keepers in neighboring prefectures and mushrooms spawning in places ravaged by rust.
These pieces of information, to Pawoo, come together and become another potential threat. She has no reason to believe Bisco and frankly, neither does the audience. So far in Rust-Eater Bisco, Milo's homemade remedies can only prevent the spread of Rusting. He hasn't found a cure yet, but he's on the right path. Bisco's search for the Rust-Eater mushroom sounds like the last piece they need, but they'll have to prove their theory in order to change minds.