Shirogane Takeru found himself inexplicably transported to a world that resembled his own in many ways, with one major difference: For nearly 30 years, mankind has been at war with the alien BETA, who have succeeded at wiping out over half of humanity and had nearly captured the entire Eurasian continent. As Takeru tried to come to grips with this bizarre new reality, he realized too late that the majority of humanity will be abandoned with the Earth, as the chosen few escape to the stars, hoping to find sanctuary.

Now, equally inexplicable reasons, he finds himself returned to the first day of his time in this alternate world. Will the experiences and knowledge he has gained allow him to make a difference?
And I'll do whatever I can to help 
Alternative IV succeed as soon as possible!
!وسأفعل كا ما يمكنني للمساعدة في نجاح أولتيرناتيف 4
Und dann werde ich so schnell wie möglich
Alternative 4 zum Erfolg führen.
Y haré cuanto pueda
para que la Alternativa IV tenga éxito.
Y haré cuanto pueda
para que la Alternativa IV tenga éxito.
Et je mènerai Alternative IV
vers le succès !
E farò di tutto per contribuire al successo 
dell'Alternative IV appena potrò!
E farei o que puder para ajudar o
Alternative IV a ter sucesso o quanto antes!
Тогда я быстро приведу 
«Альтернативу-4» к успеху!