Fall, 2045C.E. Aizawa Shuuhei, a second-year cadet enrolled in Central Military Academy's primary division, is dispatched to Aries's orbital space station on a training mission. He reunites with his younger brother, Ryouta, and his childhood friend, Nao, both of whom reside there as cadets enrolled in the preparatory division.

Then an unidentified spaceship under the control of Jararacas, a radical terrorist organization, suddenly attacks the Aries and seizes control of the main control room. With all communication lines cut off, Shuuhei and the others have no way to escape. Trapped in space, 250 miles above the Earth, they have nowhere to run. Amid this desperate situation, the cadets must gather their courage and rise to take back the Aries. As they do, they draw ever closer to the horrifying truth lurking behind this incident...

[From MangaGamer]