A little Masfit named Ruby lives above the horizon. Being the only Lunar Guardian in the world, Masfit is responsible for the night star. Once faced with the incomprehensible and inexplicable, namely the rust that suddenly began to cover the moon, Ruby goes to another world to find out the reasons for what is happening and understand how to deal with it. Incredible discoveries and acquaintances await our hero. Which? Find out by reading the magical story.