Kyokutō kyūseishu densetsu shōnen, igyō no kitai de musō suru.

When a boy takes control of an unusual machine, humanity’s battle to reclaim the world begins.

At the end of World War II, a demonic summoning ritual drastically changed the course of the world. A hundred years later, demons have become the rulers of this altered world, and humanity fights back with their magical mechs.

In this chaotic world, a boy named Keita Kawakami, who possesses memories of a “different present,” enrolls in a military academy. There, he achieves something no one else could—successfully synchronizing with an experimental prototype that no one had been able to activate.

Thrown into the battlefield right away, Keita uses his knowledge from his past life to accomplish feats that defy conventional wisdom.

—Thus begins humanity’s battle to reclaim the world.