Kyokutou Kyuseishu Densetsu Shounen, Igyou no Kitai de Musou Suru

A post-World War II demon-summoning ritual changed the world, leading to a future where demons dominate and humans use magicite-powered mechs to resist. In 2055, Keita Kawakami joins Japan's military academy and demonstrates the ability to pilot a previously inoperable prototype mech. His success is attributed to his memories of a different modern era. After being sent to the battlefield, he applies this knowledge to accomplish feats beyond conventional expectations, marking the start of humanity's effort to regain control.