In the beginning of summer, Kyoya's sister Kasumi comes to hang out in the club room. Mao convinces Kasumi she is younger than her and calls herself "Ma-chan". Meanwhile, the members of the GJ Club decide to go to the pool to escape the persistent heat... with Kasumi and her friends. The names of Kasumi's friends sound awfully familiar...

Even on the morning of the graduation ceremony, the members gather in their club room. At Shion-san's request, Kyoya follows her out to the vending machines... Once he returns to the club room, he receives a text while alone with Kirara... Finally, after school, the club's last activity together begins.