Muv-Luv Alternative

Takeru Shirogane, originally an ordinary high schooler from our world, reawakes in a parallel reality, where humanity has already lost half of the planet to the alien BETA. Now aware that he only has a few months before history repeats and humanity fails again, he vows to become a surface pilot and help XO Yuuko Kouzuki complete Alternative IV… despite having no idea what it is.