Whilst investigating the urban legends of the Undead, Kotaro Shirai stumbles upon the two Kamen Riders of BOARD.

BOARD is in pieces. Left reeling by Tachibana's betrayal, Kenzaki is forced to respond to another Undead attack.

Hirose manages to get access to Chief Karasuma's hard drive. While they search to find him, another Undead attack brings Tachibana back to the frontlines.

Tachibana reveals the truth behind the BOARD attack, and warns Kenzaki that the Rider System will destroy his body.

Hearing an urban legend about a cave where you can hear the voices of the dead, Amane drags Kotaro and Kenzaki along. However, the Centipede Undead attacks...

Kenzaki discovers the link between Amane and Chalice. An enigmatic man appears with the goal of capturing the Rider System users.

Kenzaki is captured by the mysterious Isaka, but Tachibana manages to escape the attack. He enlists help from Shiori and Kotaro to search for Kenzaki.

Kenzaki and Karasuma carry an injured Tachibana as they narrowly escape Isaka’s facility. Karasuma reveals the truth about Isaka and his organization.

While Tachibana questions his ability to become Garren and fight the Undead, Hajime struggles to understand his humanity.

Tachibana's "sickness" is cured and he is able to transform into Garren once again, but at what cost? Hajime questions Jin on human emotions.

Isaka's plans are in motion, as he seeks those marked by the Spider Undead - those with the potential to become his perfect Rider.

As the race to seal the Category Ace continues, Ikasa sets his sights on the one thing that could interfere with Garren.

The Dragonfly Undead kidnaps Amane and her mother, intending to lure Hajime into a trap. Isaka's Rider System is complete, and all that remains is finding a compatible host.

Tachibana retires as Garren, after his involvement in the creation of Isaka's Rider System. That night, the Leangle belt goes missing.

Something sinister grows within Mutsuki after he recovers the Leangle belt. Kotaro, still distrustful of Hajime, becomes entangled in an Undead plot.

Tachibana and Mutsuki arrive as Chalice seals the Undead. As Chalice fights Garren, Leangle takes control of Mutsuki again, but the fight ends quickly. After fighting the Capricorn Undead, Kenzaki brings Shirai back home. Tachibana decides to train Mustuki so he can control the belt and Tachibana learns about Mutsuki's nightmares. The Orchid Undead traps Shirai and the Capricorn Undead fights Kenzaki without his belt. Chalice frees Shirai and the Orchid Undead flees. Blade then seals the Capricorn Undead.

The Elephant Undead arrives and defeats Blade and Garren. A strange man, Noboru Shima, shows up at Shirai's house with news from Karasuma. The Spider Undead begins to regain control of Mutsuki. The Elephant Undead seeks out Chalice and wounds him. Everyone learns that Shima is actually the Tarantula Undead, though he still wishes to help. While fighting the Elephant Undead, Shima gives Blade a Rouze Absorber, which transforms him into Jack form. He then seals the Undead.

Mutsuki begins to falls under the control of the Spider Undead again. The Buffalo Undead appears and Garren and Blade rush to seal it. Shima confronts Leangle about releasing Mutsuki, but the Spider Undead persists. After Tachibana is wounded by Mutsuki, Shima attempts to properly seal the Spider Undead in order to save Mutsuki. While on the way to stop Shima, Blade encounters the Buffalo Undead and seals it.

Leangle fights Shima, but Blade arrives to stop them. While Shima and the others think of a plan, Mutsuki continues to struggle against the Spider Undead. While trying to find Mutsuki, the Woodpecker Undead begins attacking people and Garren goes to seal it. Leangle and Shima meet again to fight. Blade arrives to stop them, but is unable to. Shima allows himself to be sealed by Leangle.