I Want a Back-and-Forth Rally Chinatsu leaves for the nationals and Taiki wishes her good luck. He then learns from Kyo that Chinatsu's group saw him with Hina during the festival, worrying Taiki. He travels to the badminton nationals to support Haryū and meets Karen, who shares she is aware of Taiki's crush on Chinatsu; Taiki also learns of Karen and Haryū's support for each other, and Karen explains how they made their relationship work despite both focusing on their aspirations...