- Tetsurô Tanba
- Dr. Nishiyama / Gentetsu Nishiyama / Gengaku Nishiyama
- Toshio Kurosawa
- Akira Nakagawa
- Kaoru Yumi
- Mariko Nishiyama
- Yôko Tsukasa
- Nobuo Nishiyama
- Katsuhiko Sasaki
- Yoshihama - Assistant to Nishiyama
- Akihiko Hirata
- Environmental Scientist #1
- Hiroshi Koizumi
- Environmental Scientist #2
- Takashi Shimura
- Pediatrician
- Sô Yamamura
- Prime Minister Kuroki
- Tappei Shimokawa
- Captain of Defense Forces
- Mizuho Suzuki
- Director General of Environment Agency
- Kazuo Katô
- The Scholar
- Taketoshi Naitô
- Chief Cabinet Secretary
- Jun Hamamura
- Kida
- Kyôko Kishida
- Narrator
- Tatsu Nakamura
- Katsuko Nakagawa - Akira's Mother
- Franz Gruber
- Dr. Wilson
- Kuniyasu Atsumi
- The Scholar
- Ralph Jesser
- Party Member #2
- Shunsuke Kariya
- Leader in Crowd
- Toshizô Kudô
- The Man Who Asks a Question
- Chico Lourant
- Nigerian Ambassador
- Masahiko Tanimura
- Tayama
- Jack Ryland
- Narrator (US version)
- Yasuko Agawa
- Kida's Daughter
- Yoshirô Aoki
- Major Kashio
- Tony Cetera
- New Guinea Researcher #1
- Willie Dorsey
- Representative
- Dwight D. Eisenhower
- Self
- Dennis Falt
- UN Researcher
- Rainer Gessmann
- New Guinea Surveyor
- Mikizo Hirata
- Sanji Nakagawa - Akira's Father
- Adolf Hitler
- Self
- Kazuko Inano
- Hamako Tayama - Tayama's Wife
- Sayoko Katô
- Bus Girl in Shikoku
- Shigeo Katô
- Man Burned Out with Ultraviolet Rays
- Akio Kusama
- Official in the Environment Agency Conference Room
- Toshio Masuda
- (voice)
- Bernard L. Montgomery
- Self
- Shôsei Mutô
- Ihara
- Gorô Naya
- TV Newscaster
- Kumeko Otowa
- Kida's Wife
- Michael A. Ross
- Director General of Environment Agency / Dr. Wilson / Oone (voice)
- Keiji Sakakida
- Debate Audience Member
- Kenpachirô Satsuma
- (as Kengo Nakayama)
- Kaori Taniguchi
- Orin
- Toshiko Yabuki
- Housewife Who Asks a Question
- Mayako Yoshida
- Wife of Akira's Brother
- Yûtarô Ãsugi
- Akira's Brother
- Barry Haigh
- Akira Nakagawa
- Matthew Oram
- Professor Nishiyama
