Yo Haguro and her crew on her spacetime ship journey to Earth in the ancient past in order to find a way to save it from an unspecified event.
- Yo Haguro: a brilliant and beautiful scientist who founded her own institute to fulfill her dreams of unlocking the mysteries of the universe
- Hajime Umino: a part-timer at the institute, owner of a pendant that can turn into a cat called Koshka
- Koshka: a cat that wears a pendant, later becomes affected by the ship's timespace modulator
- Juzo Kodai: 15-year old crew member of spacetime ship
- Miyuki Moriki: childhood friend of Hajime and a crew member of the spacetime ship