They were able to set up a basic food supply system from the surface, so that wasn’t a problem. The actual problem was that a lot of the locals were trying to kill them, along the monsters adapted to the cavern ecosystem. They managed to capture some of them for research.

Few of the monsters kept as research subjects escaped but Katana managed to put them back in their place. Using a remade version of her old long sword. Which she forged herself out of bioferrite, the same oily metal that was inside some of the cavern’s creatures. Just like her old weapon, it was enchanted with runes. Katana was able to make effective use of it. Thanks to her strenght and unnatural resilience. She also wore a shield belt that helped with avoiding friendly fire.

In the end, Katana ended up harnessing of the magical power those monsters hed and used to help underground settlements and and also helped destroy those who refused their friendship. To the dissapointment of her friendly rival Shuriken. Building an OK base of operations underground.