Baku Yorozu is an invincible agent who uses his lucid dreaming ability to brilliantly rescue Nemu, a national celebrity, and complete difficult missions in his dreams. One night, Baku is suddenly attacked by a monster, the Nightmare. In his lucid dream, Baku fights against invincible foes, but for some reason, he is unable to defeat the Nightmare and runs away. Baku, cornered, encounters a mysterious person, who entrusts him with the Zeztz Driver and Capsems, and he transforms into Kamen Rider Zeztz!

In a dream, Baku somehow becomes a fugitive criminal. When he encounters the Bomb Nightmare, he transforms into Zeztz, but the Nightmare escapes. One night, Baku is suddenly summoned by Zero, who gives him an order to "infiltrate other people's dreams and prevent the Nightmare's nightmares before they happen." This means that he has to stop that bomber... Baku's mission to protect his "dream master" begins!

"To stop the nightmare, you must find the Mind's Door in the nightmare world." After receiving an order from Zero, Baku falls asleep and infiltrates Fujimi's nightmare to find the door to his mind. However, the Bomb Nightmare causes an explosion in front of Baku's eyes. If this continues, Fujimi's nightmare will become reality!? Baku transforms into Zeztz to save Fujimi and the world!

Baku dreams that he is guarding a VIP, the father of the bride, at a wedding rehearsal. Then a man appears and tries to steal from the bride, Miyuki. Baku's protection saves the day, but is he the dreamer of the Nightmare? On the day of the wedding, Baku, who is guarding the wedding in his dream, is confronted by a Nightmare who is after Miyuki. Baku transforms into Zeztz, and with the new powers he has gained from Zero, he challenges the Nightmare to a dogfight...!?

Why is the bride Miyuki the dreamer? Baku, who continues to gather information in the real world, comes in contact with Miyuki standing in front of a large tree in the park. He learns that Miyuki has a memory of the tree that could change her life. In the dream world, Baku finds Miyuki's Mind's Door and sees an unexpected scene behind the door. The Crow Nightmare appears again and attacks Miyuki and everyone else!