The vast unexplored system of pits and caves in the world is called the "Abyss." This cave system, which harbors strange and wonderful creatures in its depths, is also filled with remnants that current humanity cannot produce. The mysteries of the Abyss entice people to explore it. Those adventurers who plunge into the pit from the cliff are called the "Cave Raiders." Rico, an orphan girl living in the city of Ousu near the Abyss, dreams of becoming a cave raider like her mother and solving the mysteries of the cave system. One day, when Rico goes to explore the cave, she encounters a human-like robot. This encounter marks the beginning of our cheerful and exciting story.
