The King of Monsters on the Lonely Mountain

On an ordinary day, people are suddenly surprised to find that there is a magical power in the world, cards. People can turn them into cards through items and creatures recognized by the "system", just when they are happy. Disasters, no, costs appear, and various fantasy worlds appear. From the familiar anime world to the unknown small world, their worlds are connected to the main world. Under the influence of the system, it is difficult for items and creatures not recognized by the system to cause much harm to these visitors from another world. The thermal weapons that humans are proud of have almost become a pile of scrap metal. Humanity united and finally paid a heavy price to fight back these otherworldly creatures. Since then, the card era has come.