Nemesis

Nemesis (宿敵) was the tenth planet of the Solar System, and the base of the Black Moon Clan. The planet itself was made of the Malefic Black Crystal, which is capable of absorbing energy.

Soon after the creation of Crystal Tokyo, there was a threat to the peace made by the Death Phantom. Because he was human, Neo-Queen Serenity did not want to kill him, so she banished him to the planet Nemesis and it became forbidden to travel there.Many years later, there was another revolt on the Earth. After the battle, those who did not want to stay left Earth and ended up on Nemesis where they came under the influence of the Death Phantom.

In the Pretty Soldier Sailor Stellar series, Nemesis becomes a part time home for Hikari. After Wiseman/Death Phantom was defeated, Hikari used her Starlight Crystal to reform the planet. By the time the 21st Century rolls around, Nemesis had become a planet similar to Earth. The capital is named "The Crystal Sovereignty" and has a Crystal Castle standing in the centre