In this chapter, we learn that there are five heirs of the emperor's legacy, and that one of them is dead in the battle. There are four left, and the other two are even more powerful. We learn that the crazy old man who we ran into probably also belongs to one of these five heirs, and he's already shown himself to be a formidable opponent. The only reason why he hasn't attacked him yet is because he'd be too weak to take on the demon lord. He's too weak, in fact, that he doesn't even have the strength to take down the black prison fiend.