Jack is so big and strong, but his mind is so fragile. He constantly looks for validation from a father he didn't have. Now, he's desperate to be approved by Yujiro and twists words that put him in his mind better than Baki. I'm sorry for him, to be honest. He even modified his body to reach this level of external validation. This is a manga, but in reality, in the end, it's all the parents' fault for not giving enough love to their children.