Gunparade March

When an alien race descended upon Earth in 1945 and started massacring humanity, World War II was abruptly over. The "Phantom Beasts," also known as the Genjyu in Japanese, were an alien force that had essentially seized control of more than half of the planet. The year is 1999; 54 years later, humans are still battling alien forces for survival. Humanoid Walking Tanks (HWTs), a new generation of mecha used by Earth troops to fight the invaders, having lost far too many pilots during the conflict. The Japanese government implemented a student conscription that enlisted high school students to become HWT pilots in order to protect the future of the human race. The lives of the 5121st Platoon, which is primarily made up of recruited high school kids, are followed in Gunparade March as they battle to defeat the Phantom Beasts and maintain a regular social life.