Case 1: Start

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!