Lost in the Sea of ​​Stars Beyond the Boundary

At the edge of the solar system, the "Earth Civilization" where humans, lizardmen, and fishermen coexist has been operating peacefully for thousands of years. When the final mission of the secret debris recovery plan touched an unnamed dwarf planet, the recycler "Camel" saw the Chinese character "Xia" engraved on the metal door in the underground ruins a billion years ago - "You can not believe it, but you can't help but know.". He opened the door, and an abandoned spaceship that did not belong to any known civilization but was engraved with the symbols of the three races of the earth was waiting for him in the darkness. Inside the spacecraft, something was knocking against the wall of the ship.