From Next To Nexus and Beyond
The movie ULTRAMAN was released in theaters about one third of the way into the televised run of Ultraman Nexus, and acts as background for the series. Ultraman Nexus is set five years after the events of ULTRAMAN, in the year 2009, with Himeya Jun (Junis Red), Senjyu Ren (Junis Blue), and Komon Kazuki (Noa) taking charge as Maki's successors. Sara also returns near the series finale, serving as an advisor to TLT and Night Raider during the final attack.
The events in this movie are referred to as 'A.D. 2004' in the Ultraman Nexus series. In addition, the TLT collaborates with an unknown alien force to erase any memory about the incident in the entire human race, in order to 'protect those who experienced trauma' after the violent events in ULTRAMAN. They also cite the cause of extreme damage in the city of Tokyo due to a "violent meteor shower".
When Ultraman Nexus ended, the exact place of Ultraman Next/Nexus/Noa in the wider Ultraman continuity was unclear. No explicit references to the Ultra Garrison or any other Ultra characters were ever made. Three monsters from Ultraman Nexus (Banpira, Frogos and Galberos) appeared in the series Ultra Galaxy Mega Monster Battle (2007) and its sequel Ultra Galaxy Mega Monster Battle: Never Ending Odyssey (2008), and the same three monsters appeared in the Monster Graveyard in Mega Monster Battle: Ultra Galaxy (2009). Rather than this having any plot significance, these appearances probably had to do more with the costumes being relatively recent and therefore still in good enough condition to be used onscreen. The 2010 movie Ultraman Zero: The Revenge of Belial finally revealed that Ultraman Noa and related characters existed in another universe, one that usually had no interaction with the "M79" universe of the early Ultraman series. Ultraman Zero travels to this other universe to find Kaiser Belial and eventually merges with the power of Ultraman Noa.
Read more about this topic: Ultraman (2004 Film)