- Ryôta Ôsaka
- Ray
- Asami Seto
- Anna
- Tetsuya Kakihara
- Tyler
- Hisako Kanemoto
- Halle
- Wataru Hatano
- Eisuke
- Haruka Chisuga
- Natsumi
- Yutaka Nakano
- Tokuo Yanase / Principal (voice)
- Takahiro Fujiwara
- Takamine
- Hiroshi Shirokuma
- Goat Type Alien
- Issei Futamata
- Ummite
- Banjô Ginga
- Marui
- Daisuke Namikawa
- Professor Yoake
- Kari Wahlgren
- Anna
- Hynden Walch
- Halle
- Yuri Lowenthal
- Tyler
- Roger Craig Smith
- Eisuke
- Tom Kenny
- Ummo Alien
- Ryan Bartley
- Additional Voices
- Jennifer Beals
- Inkar
- Beau Billingslea
- Goat Alien
- Ray Chase
- Additional Voices
- Dorothy Elias-Fahn
- (voice) (as Dorothy Fahn)
- Dave Fennoy
- Tokuo Yanase
- Josh Keaton
- Ray
- Lex Lang
- Additional Voices
- Wendee Lee
- Additional Voices
- Dylan McDermott
- Yoake Suguru
- Bryce Papenbrook
- Additional Voices
- Sam Riegel
- Additional Voices
- Patrick Seitz
- Takamine
- Stephanie Sheh
- Natsumi
- Keith Silverstein
- Additional Voices
- Fred Tatasciore
- Reptilian / Marui (voice)
- Cristina Valenzuela
- Additional Voices
- David Vincent
- Additional Voices
