User blog comment:Lamango/Unused Kaiju and Aliens from the Ultra series./@comment-31679215-20171218174744/@comment-26368685-20171221090730

According to a Tsuburaya book about Mirrorman and Jumborg Ace, the Fifth Executive is Gross Go-Ne. He did not appear in the series, but is said to be the president of Planet Gross. His voice is heard in the final episode saying that he won't give up the invasion of Earth.