Kousei is preparing for the contest Kaori made him sign up for. She and him are getting closer and it makes Tsubaki a little upset. It affects her game causing her to let down her team.
But Kousei carries her home after he exposes that she sprained her ankle. He also lets her be upset and vent.
I’m really glad Kousei and Tsubaki had this moment together. Her feelings are more and more complicated but they are childhood friends who genuinely care about each other and that’s really valuable.