The Protagonist of Muv-Luv Extra, Unlimited, and Alternative.
In Unlimited he wakes up one morning to find the town in ruin, with a giant robot on top of the remains of Sumika's house and concludes that he's dreaming and wanders around to enjoy his dream, and pilot Valgernon-esque robots.
At the end of Unlimited he fails to help Yuuko complete Alternative IV and as a result they switch to Alternative V (sending 100,000 people into outer space while everyone else fights the BETA with G-Bombs.) It's implied that he later dies.
In Alternative he starts back at the beginning of Unlimited and decides to help prevent the mistakes of Unlimited from happening again, by using his memories of what happened. Soon, the future does start changing, thanks to his knowledge of what's going to happen.
Through his experiences he comes to understand the differing ideologies of the people around him and learns many things about the world, maturing as a person. Takeru gives everything to complete his objectives, losing many important things in the process, but also regaining others, always believing that the future he will obtain will be a precious one for earth.
In the spin off series, Muv-Luv Unlimited: The Day After we learn of the events and memories that Sumika locked away to create the version of Takeru that appears in Muv-Luv: Alternative. Most of these are viewed from the perspective of the protagonist Tatsunami Hibiki, a member of the Imperial Mainland Defence Force who is stationed in Seattle after the destruction of the Japanese home islands during the Babylon Disaster. However there are some scenes from Takeru's perspective that give a great deal of insight into his as-yet unrevealed experiences between the end of Muv-Luv: Unlimited and the start of The Day After. These include the deaths of the majority of Squadron 207, Mitsurugi Meiya replacing Kobuin Yuuhi as the Grand Shogun of Japan, learning of the true purpose of Alternative IV and learning of Sumika's existence far too late to be able to save her. This and other factors have rendered him nearly emotionless and almost robotically under the control of the Commander of the Imperial Royal Guard Ikaruga Takatsugu. The epilogue of The Day After shows his experiences with Hibiki have somewhat broken him from his fugue and reawaken his emotions and desire to save everyone.
Only time will tell how this boy's tale will truly end.