Arima: Hey. Milday.
Shimazu: Stop calling me that, please.
Arima: Then how about “Mio-chan, the school idol!”
Shimazu: Why do you make me so mad?
Arima: Not sure. That time of the month?
Shimazu: How crude!
Arima’s comment is offensive, but Shimazu only comments on the crudeness of it: room is left for the viewer to decide just how much of a pest they want to see Arima as. This flexibility is important for a first episode; if more unsubtle, judgemental language gets used for a character, it can dramatically change how they’re branded for the viewer for the rest of the show.
These lines are different in the Funimation dub:
Arima: Hey. So, what’s up sweet cheeks?
Shimazu: Don’t call me that. You know I hate it.
Arima: Sorry, do you prefer “Queen of the World”?
Shimazu: I’ll never understand how you can get under my skin so easily.
Arima: Good question. Maybe it’s just that time of the month?
Shimazu: Ah! You’re such a misogynist!