Age of Rust: Human Code 404

In the near future, the world is plunged into a doomsday crisis due to the out-of-control nanorobot "Rust". This micro-robot used for medical treatment mutated into a blood-rust-colored tide that devoured metal and silicon substrates, and human civilization collapsed within 72 hours. The male and female protagonists are engineers and frontline emergency doctors who have participated in the project respectively, carrying humanity's final "gene fire" plan.