Tokyo, 1969. The Earth is under attack "invaders". Fortunately, the public is not aware of it.But for organizations, A.E.G.I.S, the threat is very real, and it is - they who will stop this invasion. One day on the way to the high school, Ukiya, watching the battle between a young girl and a group of invaders. He ends up helping her and discovershe as well as the girl has the ability to cause a " gate" which only a few gifted people. As a result, Ukiya joins A.E.G.I.S, to protect the city, making every effort.