Mercury

Mercury (水銀 Suigin) is the smallest planet in the Solar System and the closest planet to the sun. It is named after the Roman deity Mercury, the messenger of the gods and one of the 12 Dii Consentes within the ancient Roman pantheon. The planet's symbol is ☿.

Mercury orbits the Sun within Earth's orbit as an inferior planet, so it can only be seen visually at dusk or dawn, and it never exceeds 28° away from the Sun.

As portrayed in Pretty Cure of the Stars
In Pretty Cure of the Stars, Mercury is the home base of Team Luminous, consisting of Luminous, Paperboy, Flaming Hot, and Rage. Team Luminous wants to take over the galaxy starting from Mercury and ending with SWEEPS-04, the furthest exoplanet from the galaxy.