The Earth has been immersed in a desperate three-decade struggle against the BETA, an extraterrestrial species who invaded the globe in 1973. In the midst of this carnage, a high school student called Takeru Shirogane awakens from a horrific vision in which he sees humanity in complete defeat. Soon after, he finds that his dream was simply recollections of his life in an other reality. In those recollections, the Alternative V project is put into action, sending hundreds of thousands of people into space as a last attempt to save mankind, while leaving the remaining billion on Earth to endure a harsh fate. Takeru joins a military installation in Yokohama, which also happens to be his former high school, hoping to improve his bleak destiny. He succeeds there.