Excerpts from Godzilla Encyclopedia

P 121

研の夢に出てきた怪人達。ヘドラが街を犯し、人間の健康や命を奪っていく………。ゴジラが現れてそれを一掃!!でも、ヘドラを生んだのは誰？

Mysterious people who appeared in Ken’s dream. Hedorah ravishes the city and kills human health and lives. Godzilla appears and wipes it out !! But who gave birth to Hedorah?

P 137

HUMANOID

大宇宙ブラックホール第三惑星人
Cosmic Black Hole Third Planet

沖縄を拠点に地球侵略を目論む。人間の姿をしているが、正体は猿人である。先兵の柳川を演じたのは、岸田森の盟友草野大悟

Aiming to invade the earth based in Okinawa. He looks like a human, but he is a monkey. It was Daigo Kusano, a friend of Shin Kishida, who played Yanagawa, a senior soldier.

[Shin Kishida (17 October 1939 – 28 December 1982) was a Japanese television, film, and stage actor. He played the Interpol Agent Nanbara in Godzilla vs MechaGodzilla 1974. Source: Wikipedia]

[Daigo Kusano (September 7, 1939-February 27, 1991) is a Japanese actor. He is from Taichung City, Taiwan. Actress Kazuko Tajima is his wife. His character, Yanagawa, is a Third Planet from the Black Hole operative who attacked Dr Wagura and Keisuke to get the King Shisa statue.]

Source: ゴジラ大図鑑　東宝特撮映画の世界 Godzilla Encyclopedia: The World of Toho Special Effects Movies, pp 121, 137