Fantasy sekai wo gendai heiki Cheat ga iku. (Novel)

Nagato Kazuya, a Military Nerd High School student who gains the ability to summon modern-day weapons and soldiers, when he reincarnated into another world. Together with his summoned Yandere military advisor, soldiers and modern-day weapons, they will conquer the land, seas & skies of a Fantasy world. These are the unparalleled existences of the Yandere harem and their stories of combat.