On an unknown continent, there is a city called Satellite City No. 9. In this city, a screw straightening worker named Rui Li at the screw factory gradually realizes the unreality of the city in her monotonous daily work. With the help of a mysterious character named "Anull", Rui Li gains the superpower of "transformation" and becomes the thief "Sirius", secretly taking action to escape from here. When the truth of the world finally unfolds before her eyes, Rui Li discovers that her real battle has just begun.