| Cast list |
| Anne Suzuki | as | James Ray Steam (voice) |
| Masane Tsukayama | as | Dr. Eddie Steam (voice) |
| Katsuo Nakamura | as | Dr. Lloyd Steam (voice) |
| Manami Konishi | as | Scarlett O'Hara (voice) |
| Kiyoshi Kodama | as | Robert Stephenson (voice) |
| Ikki Sawamura | as | David (voice) |
| Susumu Terajima | as | Freddie (voice) |
| Anna Paquin | as | James Ray Steam (voice: English version) |
| Alfred Molina | as | Dr. Eddie Steam (voice: English version) |
| Patrick Stewart | as | Dr. Lloyd Steam (voice: English version) |
| Kari Wahlgren | as | Scarlett O'Hara (voice: English version) |
| Robin Atkin Downes | as | David (voice: English version) |
| David S. Lee | as | Jason (voice: English version) |
| Paula J. Newman | as | Emma (voice: English version) |
| Moira Quirk | as | Cliff, Tommy, Additional Voices (voice: English version) |
