In 2025 AD, the sun's light faded and the earth fell into permanent darkness.
In 2027 AD, the artificial sun "Katyusha" began to operate, bringing vitality to the earth that had long been exhausted.
However, this limited light is only provided to the nobles and high-ranking government officials who live in the only four oases, while those "lower humans" who can only live in the cold and dark mutate with resentment.
In October 2063 AD, "Katyusha" was severely damaged in the battle between the World Government and the mutated "lower humans".
In 2064 AD, the "Formatting" operation carried out to repair "Katyusha" was gradually destroying the world of Devourer.
In 2074 AD, the story of Katyusha really begins!
This is a ridiculous story about rescuing monsters from humans...