In the year 1945, the most terrible creatures in existence visited the earth: bug-like entities soon to be known as Phantom Beasts. In that time of peril, mankind joined together to expel the threat, only to find that conventional weapons were useless and further damaged the earth. It is now 1999, and the student-wide draft has changed the lives of thousands of teenagers across Japan. While unwillingly fighting in an endless war that started before their births, one group of friends will experience the tragedy of death and the bittersweet joy of love as they struggle to survive.
Both of these focus on teenagers piloting mechs to combat hostile aliens who seem to manifest out of nowhere. Upon destroying the "core" (which is usually either a giant alien/"secret" or near one), all of them disappear and the area where they attacked is safe (for the time being).
Controlls fighting robots, space, future, saving the world and both main character has a women they want to protect and fight for.
Star driver is more school life and even though they have the same "elements" they both have an intressting plot worth watching!
Akiyuki lives on post-war Sentan Island, always rushing between the demands of his separated parents and his friends at school. But his carefree days come abruptly to an end when his school bus suffers an explosion, the first attack to plunge Sentan back into war. Akiyuki lives to find himself turned into a Xam'd, a mysterious creature, by the suspected cause of the explosion. Engulfed by Xam'd, Akiyuki is eventually saved by a red-haired girl, Nakiami, only to find himself torn away from those he loves. Now he must work to control and understand the creature within him, all while searching for his family and friends in a world steeped in the secrets and chaos of war.
Like Ao, Xamdou starts out with a violent event jarring the protag out of his normal daily routine. Both feature flying, creatures, different factions fighting each other, and a future that depends on the newfound powers on the main character.