If the world where we live is in inside of the cave planet????The boy getting on a mysterious railway and starts on a journey to save father who knows the secret in the planet. It is serialized in the Japanese magazine "Comic gumbo" and "Comic Zero-1", and this Sci-Fi fantasy comic revives by full color. "Salvo-1" is free. 2,3,and 4 is published one after another. Please retrieve it by the name of the author, the work name, and the name of the developer.