In 2015, UM Corporation had filed a lawsuit against Tsuburaya claiming that a document from 1976 showed an agreement to the rights to the Ultraman property. The case was ruled on back in November of 2017, which stated that the agreement produced by UMC was not authentic. UMC attempted to file motions to have the ruling overturned, which were denied in March 2018. After a lengthy legal process spanning several years, the final judgment was reached by the court on April 18, 2018, and returned to Tsuburaya Productions the copyright for the first five Ultraman series.
UM Corporation filed an appeal on May 7, 2018, claiming the District Court made errors during the trial and asked for a retrial. On December 5, 2019, the U.S. Court of Appeals denied UM Corporation’s appeal and reaffirmed the original decision made in 2018. UM Corporation can decide to take their appeal to the U.S. Supreme Court for exclusive ownership of Ultraman.
Source: Tsuburaya Productions