Sabikui Bisco (錆喰いビスコ), localized in English as Rust-Easter Bisco, is a science-fiction light novel series written by Japanese author Shinji Cobkubo featuring character illustrations by K Akagishi and environment illustrations by mocha. Set in a post-apocalyptic world, the story follows Bisco Akaboshi, an appalled "Mushroom Guardian", who is on a quest to find the elixir mushroom "Rust Eater" in order to cure his teacher.
The series has been published by ASCII Media Works since March 10, 2018 under their Dengeki Bunko imprint and is currently ongoing with seven volumes released as of March 10, 2021. It was announced the light novel is licensed by Yen Press in North America on May 21, 2021 with the first English volume of the series being scheduled to release on November 16, 2021 under the Yen On imprint.
In the future, Japan is plagued by the "Rusty Wind" which gradually rusts away and eventually kills you. The cause of the Rusty Wind is believed to be the spores of mushrooms. As a result, the Mushroom Guardians, a tribe of people who are skilled in handling mushrooms, are persecuted by society. In reality, however, it was the mushrooms that had the effect of reducing, if not curing, the rust.
Bisco Akaboshi, a young mushroom guardian who grows mushrooms all over the country to prevent rusting without worrying about public opinion, has caused such a ruckus that he has even been offered a bounty as a "Man-eating Mushroom". Bisco's goal is to find the elixir mushroom "Rust Eater", in order to cure his teacher who has caught the rust.