Muv-Luv Alternative

In *Muv-Luv Alternative*, Takeru wakes up three years after the end of *Muv-Luv Unlimited* to find himself back in his room. Although he first thinks that everything that had happened to him was a dream, he soon feels that something is wrong, and leaves the house to find that he has been sent back in time to the beginning of the events in *Unlimited*. Unwilling to accept something like *Alternative V*, he decides to help professor Kouzuki to complete *Alternative IV* and save mankind.

(Source: Wikipedia)