With the human technology advancing so fast, it hasn't been long that human can freely explore the universe.
Year 2XXX, human's fight with extraterrestrial creatures.
Hachi is one of them. She is a warrior that can be found in the front lines of the continuous war that she was born into but she was unexpectedly assasinated and died.
Hachi found herself in a world she have never seen before but only in book that she had read.