Tiga, Dyna, and Ultraman Gaia novel: The Adventure in Hyperspace

Tiga, Dyna, and Ultraman Gaia novel: The Adventure in Hyperspace (ダイナ&ウルトラマンガイア 超時空のアドベンチャー) is a sequel novel following after the events of Ultraman Tiga, Ultraman Dyna, & Ultraman Gaia: The Decisive Battle in Hyperspace.

Summary
20 years after the events of the movie, peace continues in Tsutomu's world where he and his friends are now adults. Suddenly one day, Tsutomu, Yu, Hiroshi, Kohei, Wataru experienced the same dream saying "The Red Sphere's resurrection will once again resurface the crisis of world destruction!" Will the world end? Wasn't the Res Sphere already destroyed? Must it be that monster again...? This makes an unsettling Tsutomu scream, "Gamu, Save this World!"

Ultra Warriors

 * Ultraman Tiga
 * Ultraman Dyna
 * Ultraman Gaia