Mai Otohime, who excels in all kinds of marine sports and possesses ocean knowledge that rivals that of experts, also aims for the Mitsuoka duel. However, Mai's target is Thirteen. Noren challenges her to a duel. Meanwhile, as Thirteen and his friends prepare for the duel, they have a three-way meeting. As each of them grapples with their own future, Thirteen also experiences a change of heart after his school life and encounters with his friends.