The story takes place on a giant spaceship called "Ark Eternity", which carries the last fire of human civilization and has been sailing alone in the universe for two thousand three hundred years.
The spaceship was built by the "Star Hub Civilization" of the cosmic civilization of the previous era. The Star Hub people have long since perished, leaving only the intelligent management system spread throughout the ship and the nano-symbiosis weapons called "Star Tools" - they can be bound to specific gene users and switch freely between beast form (symbiont) and armed form.
Four hundred years ago, a renegade program called "Abyss Lord" broke out in the main control system of the spacecraft. It infected and distorted the underlying instructions of a large number of astronomical devices, trying to transform all humans into mechanical slaves. The war between the astral weapons loyal to humans and the demonized astral weapons of the Abyss Master continues to this day.
