A girl got reincarnated in a parallel version of earth with highly advanced technology and people were living peacefully until a meteor that hit this earth and evolved many animals turning them into monsters and devils appearing from knowhere and massacring them.
Making them gather into cities that have not been attacked by monsters and devils and guarded by martial artist and walls towering as high at the sky, the buildings were futuristic and weapons have been combined with martial arts.
And one hundred years later in a city covered with huge towering walls a girl appeared and awakened an ability to grant any being the power to become a player thus granting them random abilities and classes beside martial arts.
Outside this city was full of monsters and no masters cannot go outside the wall as they will be killed emmidiately by monsters outside the city thankfully the walls have futuristic weapons powered by the energy everywhere used by martial artist to harness their power.
And because of that they have no power to contact other cities as something prevents their communication using highly advanced tech.