22, 2001 As a leading man of the ordinary high school students Baiyin Wu woke up , found their way into a parallel world . In this parallel world , Earth's number the past decade and a hostile alien life BETA bitter struggle with the ; and his exposure to be abandoned Zhong -cho ( the protagonist home in Yokohama, Japan ) . Wu starting this all changed the world re- joined the Army of the United Nations , and participated in the last resort against BETA , the salvation of humanity "ALTERNATIVE4" program . To this end , he became a United Nations military guards ( huge humanoid weapons, " tactical " , driver) and partners to work together . December 24 , human to give up the struggle and started to abandon the Earth ALTERNATIVE5 plan . ( Stop here before the "Muv-Luv" UNLIMITED chapter of the story ) in this three years later , woke up and found that exposure to the weapons of their own bedroom again , thought I had to return to the " old world" , however, the outdoor scene but the same and three years ago . On the calendar date is October 22, 2001 . Wu found himself after the time jump again at the parallel world full of war , and in this , he decided that the only one who knows the world of the future of human identity , and again knocked on the United Nations forces Yokohama base in order to complete the plan of "ALTERNATIVE4" door. Once again was incorporated into the weapons of 207 experimental units , again with three years of military experience and future memory, and consciousness is not lost to the partners , Looking to the challenge . Only two months or so . What weapons can achieve the purpose of human beings and whether they can overcome BETA ...