*“Humans remain nothing but a blight upon us demons.”* A boy who was once bullied in his past life is reincarnated into another world as Demon King Noct, seeking to rule over everything. However, just before achieving his ambition, he is sealed away through a cunning scheme along with his loyal generals. Three thousand years pass, and Noct finally succeeds in breaking free from his seal. Before him lies a world where grotesque monsters prey on humans, and those very humans oppress the demon race. Upon learning of the world’s devastation, Noct sets his plans into motion, gathering his former allies from the Demon King’s army to reclaim dominance. His first order of business: rescuing demons who are about to be sacrificed to monsters and exacting vengeance upon humanity. *“Kneel before me, world. My kin, commence the march!”* Thus begins the ultimate Demon King’s conquest for world domination!

Hasumi Ryuuji, the man called “the modern era’s strongest soldier”, someone who can make numerous difficult strategies a success, was transferred during a mission into the depths of another world’s dungeon. A “heavenly voice” echoed inside his brain guiding him — “Welcome, the hero from another world” — as he encounters a scene in which adventurers are been attacked by monsters. However, making good use of his superior physical abilities, discernment, and hand-to-hand combat abilities, he succeeds in easily making quick work of the monsters. In this other world, where adventurers are existences weaker than monsters, Hasumi, who can suppress his target even with just a knife, was someone regarded as a hero due to his outstanding abilities. Hasumi decides to cooperate with the adventurers he rescued, but they are attacked by a dragon, falling into a critical situation. Nevertheless, he leads his flustered comrades, coordinate them and makes an attack opportunity to appear. Moreover, after he summons modern firearms with a “weapon summoning” item, he kills the dragon in one shot by accurately targeting its weak spot. In front of this man’s tempered body and intellect, someone who is asked “Who the heck are you?” answers “I’m just a soldier”, even the mythical-grade dungeon is not a threat?! The curtain rises for the story of an ex-special forces soldier turned adventurer challenging another world!