"Ah, hello," Flower Girl says, bowing. "I-It's very nice to meet you, Misaka-sama."
Okay, Mikoto. You're the rich, elite, refined upperclassman who this girl obviously looks up to by the mere fact of your existence. Impress her. Be elegant. Be ladylike.
"Nicetameetch—er—it's, ah, very nice to meet you, Uiharu-san. And drop the—I mean, there's no need to use '-sama'."
"Ah, I apologize!" She bows again, deeper this time. "Then, it's a pleasure to meet you, Misaka-dono."
Ah, crap, she misunderstood. "No, I mean, that level of formality is—"
She bows again, almost frantically. "Misaka-ue, I beg your forgiveness for my rudeness, and would like to restate that it is the greatest pleasure to make your acquaintance!"
This is getting really, really awkward. "No, seriously, I think you're misunderstanding—"
She throws herself to her knees, forehead almost touching the ground in supplication. "Please excuse this unworthy one's vulgarity, Misaka-no-kimi! I am thy most humble serv—ow!"
Kuroko whacks Uiharu across the head with a multi-page printout of some kind or another. "That will be quite enough of that, Uiharu-san."
Uiharu picks herself up off the floor, and I can now see that she's obviously trying to hold back laughter. "Sorry!—heh—sorry. I just couldn't resist. But in all seriousness—heh—nice to meet you, Misaka-san."