Blue Box manga volume 18 features story and art by Kouji Miura.

To celebrate everyone's hard work at nationals, Taiki and the rest of the badminton team head to the beach. As luck would have it, Chinatsu's there for the basketball team's summer training camp! But instead of a fun, relaxing break, Taiki must endure the trials of an old friend to prove he deserves to be with Chinatsu!