[At the moment, a level system was introduced on this planet] The moment
its voice resonated with the heads of all mankind, the world changed. A monster called
an alien beast appeared, and one who defeated it and level it up, one who acquires an alien called skill. In order to survive in a world where
civilization has collapsed and changed, the protagonist defeats a different beast and acquires powerful skills.
Posts are irregular. (I'm also posting on Kakuyom)