Well it would seem Ayanos' brother was tagging along too, Ayano in the lead and Chiaki, followed by Yakudatsu in toe behind her.
As the trio walked together outside in search of the perfect gift, Chiaki decided to tease Ayanos' brother for previously butting his nose in to her and Aya-chans' conversation. 
"Isn't this going to be exciting Yaka-Kun! My goodness, I haven't called you that since you were atleast four years old! Anyway! As soon as we've finished buying a gift for Chiaki's Friend." 
She tried to stress the 'Friend' part so that he wouldn't get the wrong idea, and hopefully stop angering his sister. 
"Once we've finished, you can help me go... Clothes shopping! Ahehe~" Chiaki giggled with delight!
"You can help me pick the perfect dress with matching shoes... Oh yes! Lots and lots of shoes! Oh and you'll be holding all the bags of clothes I buy of course, like the true gentlemen I know you are!"
Chiaki smiled mischievously, though she was only teasing him, she wouldn't mind buying some new clothes.