The person clenching their fists in the bottom right is Sakura. Keep in mind that it is Naruto that is the driving force behind Sasuke and Sakura's quest for power Sasuke needs to be stronger than Naruto as being weaker than Naruto to him is synonymous with being lazy and not sacrificing enough. And Sakura doesnt want to feel defenseless anymore and doesn't want to sit around while other people risk their lives to protect her.
And yet with all their hardwork Naruto still proves to be far ahead of them, and part of them is jealous.