With their tour of the nine Kamen Rider Worlds complete, the Hikari Studio group returns to their home world, finding it as it was before the monsters appeared. Tsukasa is the only one who feels something is not right and questions the reason for the journey. Before Yusuke or Natsumi can attempt to answer, they encounter the violinist Otoya Kurenai, who thanks them for saving the world and tells Tsukasa that he earned a world of his own for his journey. As Natsumi goes out to see her TG Club friends and teacher for a high school reunion, Tsukasa and Yusuke have a short encounter with Narutaki who congratulates him on getting his own world.

After Tsukasa suddenly loses his powers, he learns from Kaito that he is actually in the World of Negatives. He later is seen by a talent agent and is offered to be signed onto his agency to become an idol. Although Yusuke acts as the voice of reason, he gets caught up in the fame seeking as well. Meanwhile, after her school friends return while waiting for Chinatsu, Natsumi that suggests that they should dig up the "treasure" they buried together, only to find that a parking lot was built over it and learning that Chinatsu moved their treasure prior. Once, Tsukasa finds Natsumi, he attempts to tell her that they are not in the real world, but Natsumi refuses to accept this as she runs off to the TG Club's hideout where she also meets the World of Negatives's Natsumi.