A whole chapter devoted to the leader of Urumin's group. This is the kind of backstory that the author can spend time to tell now that the story is serialized. I have recently been watching Zombie Land Saga and Airu here reminds me of Saki from that show. They are both former delinquents and the leaders of their respective groups.
It was also nice to see our brave MC Kimiya on the last page. He must have been a fan from the very early days.