Sailor Moon series
In the Sailor Moon metaseries, Neptune was the home planet of and the planet that was protected by Sailor Neptune.
In the manga, Triton Castle was known to orbit the planet, and it was the castle of Princess Neptune.
Neptune, out of all the planets, is the fourth planet with the most moons, with at least fourteen of them. The major ones are Triton, Nereid, and Proteus.
Neptune is the ruling planet over the Zodiac symbol Pisces (Michiru Kaiou was born under the sign of Pisces). Neptune is also associated with idealism, imagination, self-sacrifice, spirituality, creativity, sensitivity, and compassion.