iamtouhou
The Earth was on the brink of extinction when an alien species came to save it in exchange for a place to live. The Tyrans.
Tyrans are like humans but they can be reborn and be given a certain ability in exchange for their memories. Both species agreed to live peacefully until one day, a weapon is develop to destroy the Tyrans.
Kohaku Inoue is on the job when she save a Tyran, Meena, who does not speak. A series of unfortunate events unfold when the two of them met.