In Qingyuan City, where the rust plague is spreading, the girl Su Wan has a cursed brand "Rust Lock" imprisoned in her right hand. In an encounter, she swallowed the metal monster "Flayer", but she was wanted by the official organization "Rust Cleaning Department". What's even more frightening is that the rusty locks are gradually eroding her body. The only hope is hidden deep in the "Rust Heart" - she reached a contract with Mana, the "Crimson Mother" of the source of will, and became the "engineer" to repair its broken foundation. Clues point to the missing father - an engineer who participated in the "Crimson Heart" project. Faced with the pursuit of the Purification Department, the corrosion in his body, and Mana's doubts, Su Wan ventured into the heavily polluted industrial zone in the west of the city to search for his father's notes. She must find a chance of survival for her brother and herself between the power of the Rust Lock and her father's secret before being eliminated, swallowed, or assimilated.
