The "Tears of the New Moon" was a great disaster that brought down a poisonous rain "Blueshist" that could kill people if exposed to it. More than 100 years have passed since then, and mankind has finally begun to overcome the disaster. In the "Nest" settlements scattered throughout the devastated world, beside those who are living strongly, there are humanoid "Megas" equipped with a dual-thinking AI. The year is 2242 A.D. Megas, who had fallen asleep with no memory of their past, finally awoke--.

[Source: Crunchyroll News]