Inside Mercury, Japan builds a large-sized solar space power plant. The plant supports Earth with its large solar energy supply but suddenly there is an abnormality at the Saint Elmo plant. To pinpoint the problem, Earth sends several technicians to fix it.
| Actor | Role |
|---|---|
 Toru FuruyaIssei Yuuki (voice) | Issei Yuuki (voice) |
 Hideyuki TanakaJeff (voice) | Jeff (voice) |
 Ichiro NagaiChief Kodai (voice) | Chief Kodai (voice) |
 Kei TomiyamaManabu Yamato (voice) | Manabu Yamato (voice) |
 Keiko HanMayu Hoshino (voice) | Mayu Hoshino (voice) |
 Masako NozawaMī-kun (voice) / Gugi (voice) | Mī-kun (voice) / Gugi (voice) |
 Reiko MutohHannah (voice) / Narration (voice) | Hannah (voice) / Narration (voice) |
 Koji TotaniTsuyoshi Yūki (voice) / Yuri (voice) | Tsuyoshi Yūki (voice) / Yuri (voice) |
 Kozo ShioyaJin Ren (voice) | Jin Ren (voice) |
 Leiji MatsumotoLeiji Matsumoto (voice) | Leiji Matsumoto (voice) |
 Masako IkedaFū the Alien (voice) / Yūki's Mother (voice) | Fū the Alien (voice) / Yūki's Mother (voice) |
 Noriko TsukaseYūki's Grandmother (voice) | Yūki's Grandmother (voice) |
 Ryuji SaikachiYūki's Grandfather (voice) | Yūki's Grandfather (voice) |
 Yoko AsagamiSimba (voice) | Simba (voice) |
 Yuriko YamamotoEri Yūki (voice) | Eri Yūki (voice) |