Kai and the group are still in shock over what happened with Kourin and what Aichi said. Then, Naoki suggests to undergo intensive training from Leon, although Kai and Misaki are reluctant. Nevertheless, with Shin coming along and leaving Card Capital under Ren's supervision, Kai and his friends go to Leon's home island. Once there, Naoki and Kamui begin their training under Leon's tutelage. Naoki repeatedly cardfights against Leon but loses every match. Believing Naoki is not making any progress through these repetitive fights, Leon then decides to have him reach a nearby islet before battling him again. Later joined by Kamui, Naoki tries to swim among other various methods to reach the islet, but all of their attempts fail due to the current. It is not until Naoki and Kamui see Sharlene effortlessly fishing in a boat close by them that they see the error of their ways.
By dinnertime, Naoki and Kamui return to Leon and present him with fruit that only grows on that islet as proof that they have completed Leon's test. So, Naoki has earned another chance to fight Leon. Now knowing that passion alone not being enough, being adaptive, and experimenting were the lessons that Leon was trying to teach him and Kamui, Naoki uses a modified deck to push Leon close to defeat. Despite his best efforts, Leon still wins but compliments Naoki's perseverance as his strength and has now learned to take full advantage of it.
