Since Kaori can’t go get dessert with Watari, she takes Kousei instead.
This is also when she asks him to accompany her for next violin competition. He refuses and she gives him some tough love about what it means to be a musician.
Then Kaori and Tsubaki totally troll him. They tape the sheet music everywhere and play the score over the loudspeaker at school. It’s pretty epic and hilarious.
Finally Kousei agrees, twenty minutes before the competition, because Kaori gets really emotional about it and starts crying. The episodes ends with Watari and Tsubaki on two bikes trying to get them to the concert hall on time.
Kaori does mention her heart in the speech she gives Kousei. He takes it as her metaphorical, emotional heart but I’m thinking she meant her literal heart and that there’s something wrong with it.
But we’ll see.