This must be Tohomania's doing.

1, Mizuno

This Mizuno dosen't mean the family name of Toho vamp actress. It is the family name of a monster man in "The Human Vapor" (1960, Japanese title: Gas ningen dai 1 gou). The actor who played this title role is Mr. Tsuchiya Yoshio as you know. Mr. Tsuchiya played Mizuno again in "Teito taisen" (trans. Imperial Metropolice Wars). Mizuno in "The human Vapor" is altered by a mad scientist, but Mizuno in "Teito taisen" is a scientist.
By the way, Mr. Ichise Takashige, producer/ director of "Teito taisen" had remade TV series "Ultra Q" as independent 8 mm film "Ultra Q No.29: Yami ga kuru!" in 1980. In it, the original TV series players, Sahara Kenji, Saijou Yasuhiko and Sakurai Hiroko, appeared specially.

2, Dr. Tadokoro

In "Tidal Wave" (1973, Japanese title: Noppon Chinbotsu, directed by Moritani Shirou) , a geophysicist Dr. Tadokoro predicted that the Japan Islands would go down under the sea. In after years, another Dr. Tadokoro predictes the volcanic activity in the film "Bugs".
The actor who played Dr. Tadokoro in "Bugs" is Mr. Yamamoto Ren. He appeared in many Toho kaiju eigas (monster movies). For example, an elder brother in Oto Island ("Godzilla" 1954), the man who was mistaken for the Human Vapor and arrested by police ("The Human Vapor"), etc...
Though I don't know Mr. Nishikiori, director of "Bugs", well, I know there was an assistant director named Nishikiori in about 60's in Toho... Are they relative???

3, Rossirica

Rossirica - it is the unreal nation in the film "Mothra" (1960, directed by Honda Inoshirou). Of course, this name was synthesized between "Rossija (Russia)" and "America". In a epsiode of TV anime series "Cutey Honey f" (1997), it isn't horror though, the Rossirican Navy appeared.

To be continued...