Yeah, dude was used to selling his body and his boss didn't do anything about it. So when it blew up in his face, that's when he decided to get rid of him. Why the hell he is acting like a victim when he made the boy work just to appease him, I wouldn't know. I would say the mc had to work for food, but he was also given the job to cook for everyone with shitty supplies. Just goes to show that everyone is a hero in their own story.
Honestly I think koku was so used to exploiting kids, making money off them yet underfunding their activities like the horrible little man that he is and getting rid of them when they were no longer useful, that he didn't even recognise that...that's what he was doing.
Like I've read multiple series where there's a really complicated exploitation Vs love dynamic between a main character and someone they view almost as a parent, this guy is RIGHT IN THE DAMN GUTTER. He could not get worse short of being his pimp 🥲
I know the era they're in was supposed to be pretty dang awful for folks who lived in the peasant and ostracised classes (lots of famines, I believe horrible actions like having to leave family to die in the mountains, and poverty & famine caused cannibalism, as was common all over unfortunately ) but by god people like him really really love to just revel in the things they gain by hurting others.