This is a story just a little bit in the future… The earth has been invaded by mysterious extraterrestrial life. In order to resist against them， people form a new organization called ”The Globe Invaders terminators Organization，” commonly named G.I.O. It belongs to the International Security Organization. Three beautiful girls are chosen to be candidates for G.I.O-Rangers who are going to be the center of the G.I.O. activities. They are Yuki Saeba who is a strong-minded and arrogant investigator， and Ai Minato who is a fainthearted with no fight experiences and also a trainee of space flight， and Ren Yuki who is a taciturn soldier and obeys orders with faithfulness. Those three girls with totally different characters and ways of thinking and careers are forced to join hellish special training under a hard-hearted instructor named Shina for six months. Shina，a Spartan military type coach， treats them as if they were not human beings，gives harsh punishments to anyone who can’t catch up with his training and never forgives anyone who makes a complaint and retorts. Those three girls try to stick with the training desperately even though their bodies and souls are totally wasted and torn apart. However， Yuki’s got a problem. She can not stand herself unless she is always on the top of the game. When she is beaten by Ren during the training， she starts to bring a discord into the relationship between the three.