I can't imagine anyone daring to truly "bully" the princess, especially in Japan where every student must know who she is. "Rowdy" behaviour by 8 year old boys... oh, the HugeManatee for the uber stuffy Imperial Household Agency.
William was a bully when he was young. But he was disciplined where appropriate and taught respect where needed, and he grew out of it, and became a fine young man.
That’s what it takes.