How do I keep aogami carbon steel from rusting?

Aogami carbon steel rusts because it lacks the chromium that makes stainless steel rust-resistant, so the only way to keep it from rusting is to never let moisture sit on the blade — wipe it dry immediately after use and store it in a dry environment.

Aogami Super (Blue Super) is a high-carbon steel (1.45% carbon) with no chromium content (only 0.4%), meaning it will rust if left wet. After every use, wash the blade with mild soap and warm water, then dry it thoroughly with a clean towel — do not air-dry. For storage, keep the knife in a dry area, ideally in a saya (wooden sheath) or on a magnetic rack away from humidity. A light coating of food-grade mineral oil or camellia oil on the blade before storage adds an extra barrier against moisture.

Building a patina — a thin, stable oxide layer — is the traditional way to protect the steel while adding character. Cutting warm protein, especially meat with blood (like fish or steak), will encourage a nice, even patina over time. Many enthusiasts treat patina development as a form of art; you can see examples and techniques in the Kitchen Knife Forums patina thread at https://www.kitchenknifeforums.com/threads/my-favorite-color-is-blue-a-patina-thread.299. Avoid cutting acidic foods (lemons, tomatoes) on a new blade until a patina has formed, as acid can cause uneven or aggressive rust spots.