Behind the battle of the Hero and the Demon King

Behind the battle of the Hero and the Demon King summary:

The battle between the Demon King and the Hero will decide the fate of the world. Verna, the son of a nobleman, who remembered that he was reincarnated in the world of an RPG game, he was originally a mob who died without a name. The reason is probably the attack on the royal capital by the Demon King's army. Judging that, Verna mobilizes all the knowledge and wisdom of his previous life to find a way to survive in order to avoid a tragedy.Train yourself with the knowledge of the game and become friends with the Hero Mazel. The game start event "Monster Runaway Stampede". On the battlefield where the Hero is absent, Werner shows a lion-like performance by thwarting the aim of monsters that no one has noticed, and will change the history of the game!? The full-fledged war fantasy of mob characters who struggle behind the legend begins here.