Infinite Upgrade Player System

I don't know when, something called a "door" appeared in the world I live in, which connects to other dimensional planes. You don't know what you will face, and everything will become unknown from the moment you step into "it"! What you face may be a "god", or a "demon", demon hunters! Pick up your courage! Pick up the sword in your hands! For your home, for your loved ones! No matter what it is! Defeat it! This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.