Need help, can't see the kanji in the untranslated bubble.
「利根姉さんったら...でも欲張る姉さんも可愛い...」
A more literal translation for the second half would probably go "...but a greedy Nee-san is cute too..."
欲張る、よくばる (yokubaru). To crave over or want something in a greedy or avaricious manner. Including like say, a spoiled kid (or even those not so spoiled) whining over a toy or snack they want. Here, Chikuma initially thought Tone bought two balloons for herself, which would be kinda greedy.
(欲張る also has less wholesome uses, in which case it can be translated as lust, depending on context.)
Hey, Chikuma!I got them!This is yours, Chikuma!Nee-san...!!!!!Geez, Tone-neesan...
But still, her covetousness is cute too...Yeah!Isn't it good, Nee-san?One more balloon, please!