With Tachibana walking off without offering aid and Karasuma, BOARD's president, no where to be found, Kenzaki and Shiori, one of BOARD's surviving members, set-up a new base of operations in Kotaro's home. Kenzaki, Hirose, and Kotaro successfully began tracking and sealing any active Undead in the area. But when Kenzaki starts tracking down his renegade partner Tachibana, he encounters Chalice and tries to befriend him after learning of his identity, Hajime. Kenzaki was later kidnapped by men working for Isaka to be used in an experiment to test the human/Category Ace fusion ratio by pitting him against the Trilobite Undead, his fusion rate increasing upon seeing Hajime with his captors before Chalice gets involved as well before Garren provides backup. Kenzaki learns that Hajime is an Undead, confronting him before they fight until the Zebra Undead start his attack. Kenzaki started to believe that there's some good in Hajime and that he's not the monster he originally thought him to be.
Kenzaki does everything in his power to keep him from reverting to his true form. Hajime begins to lose control and his impulse as Joker comes forth with the Stone of Sealing creating an army of DarkRoaches to eliminate all humans. In the end, Kamen Rider Blade is the only one to combat him head on, both equal in power, intend on saving the Earth and Hajime from himself. In the finale, Kenzaki sacrificed his humanity in order to save Hajime, thus becoming the Navy Joker. Hajime is allowed to keep his Human Spirit card to maintain his disguise and stays with the Kurihara family for the rest of his life, but still remembers what Kenzaki has done for him, and if he and Kenzaki cross paths again, fate will step in and force them to fight.