In this chapter, we learn that Valkyrie is talking to a bot bird, which means that he's not interested in seeing Homura. We learn that the jailers can treat prisoners as they wish, but they can also take away their food, put them in solitary confinement, and punish them if they do manage to beat one of the prisoners. This is a big deal, because no one has ever taken down the black rock, which is the most important stone in the mines. It's hard to believe that anyone would ever take it down, but if you beat it, you're going to get a ton of metal, so you'll probably die before you know it. But if he manages to beat the prisoner, he'll get the metal either way, because the jailer will have to take away his food or put him in a solitary confinement. He tells us that he has the authority to do whatever he wants with the prisoners, and that's why he keeps them locked up like that.