The final season introduces 3 new senshi, the Sailor Stars, Sailor StarFighter, Sailor StarHealer, Sailor StarMaker. Also introduced are several evil senshi, Sailor Galaxia and her Sailor Animates: Sailor Iron Mouse, Sailor Aluminum Siren, Sailor Lead Crow, Sailor Tin Cat. The Animates were trying to find the star seeds for the planets of the solar system.
If they could find them all Sailor Galaxia would have total control over the universe. She already had control of about 80%. The world of the Three Lights, pop idol group and the Sailor Stars, had been destroyed by Galaxia and they had fled to Earth in search of their Princess Fireball, who has dissappeared. The Sailor Stars are very ruthless and come into conflict with the Sailor Scouts often. Also introduced this season is ChibiChibi a little mystery girl that follows Serena/Usagi home one day. All she will say is "chibi-chibi" so that's what they call her.