The New Gate - Volume 1 (Light Novel‪)‬

In the deepest level of the dungeon known as the Gate of the Otherworld, Shin was locked in battle. His opponent: the final boss of THE NEW GATE, a VRMMO that had transformed into a deadly death game.
After a fierce and grueling fight, Shin emerged victorious, freeing the trapped players from their digital prison. But just as relief washed over him, a mysterious door at the heart of the dungeon suddenly opened-and in the next moment, Shin lost consciousness.
When he came to, what lay before him was the world of THE NEW GATE-not the game, but the real thing.