Bokurano by Mohiro Kitoh

Ours

In a gripping tale of sacrifice and existential dread, a group of middle school students find themselves thrust into a harrowing game of survival when they are chosen to pilot a colossal robot to defend Earth from alien threats. As they take turns piloting the machine, they soon discover the devastating cost of their mission: each battle demands the life of the pilot. As the children grapple with the weight of their fate, they confront profound questions about life, death, and the value of humanity, all while the clock ticks down to their inevitable destinies.