I lead the Army of Darkness -Isekai story

Andrew Perez, the #1 in the armored combat league (and secret weeb), was resting before his debut match. However, right before he got into the arena, he was summoned to another world? and why the hell was he thrown out on his ass right after being summoned? Banished to the edge of the border of the demon king's territory, he fights and defeats an army of demons. As he is about to collapse, a screen appears. {You have met the requirements for a class. would you like to change your class to shadow captain?} Being on the verge of passing out, he clicked {yes} and fell asleep. Warning: Curses and gore. Lots.