I know some people treat her like a meme, but she's aware of herself and strives to become the sort of person she wants to be. She didn't naturally become a fearless leader overnight, she's had to overcome obstacles regarding confidence and her ability to lead.
Adding onto that, she's hardworking as FUCK. If she wants something, she's having it, even if she breaks her whole body in half along the way. Plus she's the student council president, and that can't be an easy job ~especially when you're school's on the verge of death~
She isn't daunted by her shitty parents. The parents who are basically forcing her into an arranged marriage and raise her up to be the perfect heiress of the Kurosawa Family. She's obedient, but at the end of her SID she realises that her life is her own to control and says that if she's going to be pushes into an arranged marriage, she's running away. What a badass.
She's! So!! Cute!!! Her fucking buu bUU DESU WAs and look at that adorable fucking mole. Don't tell me she's not cute because she is okay.
HER PASSION. You would think that the oldest and most elegant daughter of the Kurosawa Family wouldn't give a flying fuck about idols, right? WRONG. Dia loves idols and she's damn well going to be one. She only gives up on that dream when her best (and only :( ) friends cut themselves away from her, but once they're back, she's back in action!!
Holy fuck she's funny. It's completely unintentional, but she's hilarious. Everything she says is 100% serious at all times and that only increases the comedy factor because she says a lot of (again, completely unintentional) absurd stuff.
She loves Ruby!! She gives her lap pillows and dotes on her all the time. They have arguments, yes, but they're close. Their relationship is adorable and really, really interesting to look at because they're practically two sides of the same coin (may write up an analysis of that later). They sincerely love and care for each other, and being a little sister myself, that really warms my heart.
She's a complete flip of the ideal Japanese woman and the 'ojou-san' archetype. On the surface, she looks like a carbon copy of those two: long, black hair; successful and rich background; and refined in speech. However, once you actually get into her personality, you find that she's pretty much the opposite of 'elegant' -- she's awful at communicating and working out her feelings, she's awkward as HELL, she's so passionate it's almost scary, and she freely puts her foot down whenever she feels like it. What a badass x2