I think the king of all comedy reliefs in tokusatsu would be the late Yuu Fujiki, who played comedy reliefs like TV exec Kinsaburou Furue in King Kong Vs. Godzilla, photographer Yoshito Nishibe in Atragon, reporter Jirou Nakamura in Mothra Vs. Godzilla, and a cameo appearance early in Space Amoeba!
He was also in many of Toho's Young Guy and Crazy Cats films, appeared in episodes of Mighty Jack and Rainbowman, and was also a regular (the Jounan Sports Club owner Seiji Oomura) in Ultraman Leo!