Ayanokouji's relationship with Karuizawa deepens, while the aftershock of his perfect mathematics score ripples through the school. Horikita asks to join the student council, and is accepted by Nagumo. And summer vacation brings with it no rest, but another special exam—a reprise of the earlier deserted island test. Except this time, it'll be a battle royale with all three grade levels duking it out against each other!