A.S. (Ad Stella) 122― An era when a multitude of corporations have entered space and built a huge economic system. A lone girl from the remote planet Mercury transfers to the Asticassia School of Technology, run by the Beneritt Group which dominates the mobile suit industry. Her name is Suletta Mercury. With a scarlet light burning in her pure heart, this girl walks step by step through a new world.

Hodaka, a high school boy who moves from his isolated island home to the city of Tokyo, who immediately becomes broke! After finally finding work at a shady occult magazine, the sky rains every day until amidst the hustle and bustle of the big city, he meets a young woman called Hina. She lives a cheerful life with her younger brother, but also has a certain power: to stop the rain and clear the sky.