I see Tsuyu-san has noticed the difference between them at last. And she getting pissed. Not good for Tatebayashi-san.
AFTER TRANSLATION - Tatebayashi-san is also an idiot for calling Tsuyu-san old. She should've gracefully accepted the onee-san thing and moved on, instead of creating another enemy who may now cheerfully stand by and watch as Shiranui inserts large objects into Tatebayashi-san.
Updated
I-is that a no?WHAT?I-I'm younger at age compared to Tsuyu-san.Well... actually,That's why when it comes to that, I think it's more appropriate for me to call Tsuyu-san "big sis"......UmmIs it fine if I call you "big sis"?!Tsuyu-san is 21 years old, right?