>>279918315 (OP)I read Baki's storytime, so from the way I understood Yujiro, he's like a child who's the strongest in the world and wants everyone to know that he's the alpha male. That's why he does those kinds of things, from opening a bottle in an impressive way by cutting off its beak with his hand to raping men and women. He does it because he can and no one can stop him, to show others that he's the alpha male and that the rules of the weak don't apply to him.
Another related element is that Yujiro wants to be an animal, a beast that doesn't respect the laws of society. This contrasts with Pickle, who is genuinely more beast-like than Yujiro, but he does it out of instinct, while Yujiro does it intentionally. Pickle raped the reporter because his animal instincts told him to. Yujiro rapes knowing it's wrong.
But if Yujiro wants to be a beast, then why does he sometimes dress well and eat high quality food? To impress and show that he's at the top, that he can do both without respecting anyone or anything (except for people who are strong enough for him to give them some respect like Baki, Doppo or Hanayama)