It's a cycle. You see the lines on his neck? Maybe the same thing happened to him last time and the cut off his heads. And another person said, the kids are the next hounds.
Which guy? Iruma lost his memories just likes the other because the power of one of the six fingers member. If u asked about which arc its amusements park arc (which honestly makes me kinda aware we have a lot amusement park kinda moments in the story).
Also, if you're talking the small guy he's also a member of da six finger. But if you're talking about the guy in the last panel, apparently he's kalego big brother who hates iruma because he is human.
It's a cycle. You see the lines on his neck? Maybe the same thing happened to him last time and the cut off his heads. And another person said, the kids are the next hounds.