That legendary superweapon from history? That’s me

Synopsis

500 years ago, the world was engulfed in the Magical Great War.Amid the conflict, a special soldier—who had a combat AI called DEMON implanted in his head and a superweapon capable of destroying even mountains embedded within his body—dominated the battlefield.“Cross, stop looking down and pay attention! Are you even listening?!”Even if you tell me that, how am I supposed to look up…?Because the soldier shown in that historical footage from 500 years ago, fighting with the ferocity of a demon god…is none other than me!!