None of them tried to prove themselves better than her, to whom Yukino refers as imbeciles.
It helps make you a better person.
It was also mentioned that the trio has been to the amusement park where Haruno would mess with them, resulting in the fear of rides for Yukino.
Her upperclassmen harassed her frequently—all of this due to the fact that she is beautiful and popular among boys, thus attracting unpleasant attention.
Her obsession for Pan-san is known by both and Hachiman.
Despite her calm and reserved demeanor, Yukino has a somewhat frightening side.