In the "Continent of Aria", a genetic disaster called "Scarlet Code" swept across the world - 90% of humans were transformed into "Bone Eaters" with a strong desire to bite living creatures, and the virus in their saliva could complete the infection within 30 seconds; among the remaining survivors, 10% awakened weak "mutant resistance" (such as delaying virus infection, short-term deterrence against Bone Eaters), but were regarded as "unclean" by the powerful "Purification Church" and hunted down.
The protagonist, Lin Ye, was once a "demon hunter" trained by the church. He defected after discovering that the church used living people to experiment with viruses. The old-era military tablet he carried with him contained key data for suppressing the virus. During his escape, he met a group of survivors with their own unique skills: Aila, a mechanic girl who can modify abandoned mechas, Lao Jin, a former gangster doctor who masters suppressive therapy in the early stages of infection, Amo, a mute boy who can predict the movements of bone eroders through whistles, and Su, a mysterious wandering priestess whose bloodline seems to be related to the source of the disaster.
The five-person group drove the modified armored vehicle "Rusty Iron" through the ruins that were strangled by the Bone Eater and the Church. They not only want to decipher the secret of the Scarlet Code, but also find a true pure land for themselves and their kind in the gap between humanity and survival - but they don't know that the Bone Eater is evolving, and the Pope of the Church is no longer "human".
