Popular national talent Nemu has been kidnapped by a criminal organization! Just when everyone is about to despair, the strongest agent appears! "Code number: Seven, carry out the mission." Seven fights with gusto! He rescues Nemu, and the two of them get along well... Or so Mozu, an ordinary, good-natured young man, dreams. Whenever he tries to help someone, he somehow ends up suffering nightmarish misfortune. But the only place where he can become his ideal self is the dream world. However, a nightmare monster, Nightmare, attacks this dream world! Mozu takes action to stop those who are invading his dreams and trying to erode reality as well. He may be ordinary in reality, but he is the strongest in dreams! When Mozu believes in his dreams, Kamen Rider Zeztz awakens.

For some reason, Moko (Ryutaro Imai) has become a fugitive in his dreams. When he encounters the bomber Nightmare, he transforms into Zetts, but the bomber escapes. One night, Moko is suddenly summoned by Zero (voice: Jiei Kabira) and given the command to "infiltrate other people's dreams and prevent Nightmare's nightmares from happening." This means that he must stop the bomber... And so begins Moko's mission to protect his "dream owner"!

The dream owner this time is Detective Fujimi. But does Fujimi really want the bombings to continue? Deep in his psyche lies a locked door of the mind — and if this final door opens, nightmares may pour into reality! Even being all-powerful in dreams, Makoto (Baku) outside of them is just an ordinary young man. Now, as agent ZETTZ, he faces a real confrontation. The true fight begins now.

Moko infiltrates a wedding rehearsal. The groom is the heir to a wealthy family, and the bride's father is a powerful politician. Could the assassin be from a rival faction, or...? In order to prevent a tragedy like the bomber from ever happening again, failure in the mission is unacceptable. With Z Gear and a new Capsule "Wing" in hand, can Moko become a true agent? Fly towards your dreams, Z!

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!