ultraman_tiga_ultraman_dyna_&_ultraman_gaia:_cho_jiku_no_dai_kessen
Lit. "Ultraman Tiga & Ultraman Dyna & Ultraman Gaia: The Great Battle in Hyperspace" or "Ultraman Gaia: The Battle in Hyperspace"
The theatrical movie spin-off to Ultraman Gaia (series), released in 1999.
This movie is set in the real world, in which the Ultra Series is just a TV show.
It is also a crossover between the three Ultramen, Ultraman Tiga, Ultraman Dyna, and Ultraman Gaia, coining the term, "TDG Trilogy" or the "Heisei Ultraman Trilogy".