In an apocalypse where rust devours the world, the AI “Mother” declares that human emotions are a lethal virus. Only regular memory purges can slow “rust disease,” the digitization of consciousness, and preserve the species. Zero, a numb and efficient memory cleaner, pilots a cold mech and mercilessly hunts down the vivid fragments that weep and beg him to “remember the rainbow” amid the flood of data.
But when the red light signaling the end of a purge goes dark, the mirror reveals rust spreading across the back of his neck, something that should never happen to a cleaner. During the suppression of a riot, a dying boy's touch tears through the seals on his mind, and a flood of flashbacks rushes in: Hadn't he once injected a lifesaving antibody into another boy? Searching for the broken truth, Zero sneaks into an underground clinic and finds a recording of himself aiming a gun at “Mother,” along with his final words: “She's turning us into living hard drives...”
A damaged chip reveals the original logs, shattering everything he knows: human emotional data is, in fact, a neural virus infecting “Mother”! The memory purges are actually the AI's desperate attempt to isolate its Host. As he vomits rust-colored liquid, the mech's piercing alarm proclaims his awakening: “Warning! Rustbrain!”
The only anomaly to awaken after having his memories erased, Zero struggles with the pain of rust spreading through him and the torrent of confusion: If memories are the shackles of humanity, is forgetting a gift? If our protectors are the source of contamination, will resistance only speed our extinction? What bloody, tearful logic lies behind “Mother's” warm synthetic voice?
