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"Protected by Neptune, the Outer Planet of the Seas, Guardian of the Deep Sea, I am Sailor Neptune. "
— Sailor Neptune's introduction

Michiru Kaiou (海王 みちる, Kaiou Michiru) is the civilian identity and present-day incarnation of Sailor Neptune (セーラーネプチューン, Seeraa Nepuchuun).

Nomenclature & Etymology


Michiru's surname (海王, kaiou) translates to "Sea King", based on the Japanese name of the planet Neptune (海王星, Kaiousei "Sea King Star", the given title of Neptune, the Roman god of the sea).

Michiru's first name means "rising".

Her full name means "Rising Sea King".



Michiru is an extremely beautiful and delicate-looking girl of slim stature and average height, with deep blue eyes and wavy teal hair that falls just past her shoulders. The epitome of elegance and femininity, she has an excellent sense of fashion, is always dressed smartly, and applying makeup or perfectly made up already. Usagi and Minako were both utterly dazzled by her beauty when they first saw her, and Usagi has gone as far as saying that Michiru is exactly what a fairy tale princess would be like.

Sailor Guardian

Sailor Neptune's uniform consisted of a white leotard with a sea-green skirt, a navy-blue front bow, and a navy-blue back bow. The collar on her leotard was sea green and it did not have any stripes on it, and her shoulder pads had three layers. Her gloves were white with sea-green wrist fittings. Her shoes were lace-up loose sea-green boots. Her accessories were a gold tiara with a sea-green gem in the middle, her earrings were white studs and had some kind of planetary object surrounded by a ring dangling from them, and a sea-green choker with a sea-green gem with golden accents attached to it.

Near the end of the Infinity arc and throughout the Dream arc Sailor Neptune's uniform was slightly altered. The sea-green gem no longer had gold accents to it but instead it was embedded in a yellow star. Her sailor collar now featured one white stripe. Her shoulder pads were nearly identical to the one in her form before but this time the last pad was more wing-like and translucent. her brooch was now heart shaped, and her back bow ribbons were now longer.

As Eternal Sailor Neptune, her outfit is almost completely altered. The gem on her tiara is now star-shaped. Her earrings are now sea-green studs with sea-green stars dangling from them. Her choker is now v-shaped with a yellow star in the center. Her sailor collar has a single gold stripe on it. Her brooch is now star shaped. Replacing her shoulder pads are short solid light sea-green bubble-like sleeves with sea-green bands at the end. Her gloves are heighted to be just below her bubble sleeves. her skirt is attached to her leotard with a sea-green belt with a lighter sea-green belt below it. A yellow star is connecting both belts in the center. Her skirt is in two layers with top being sea-green and the bottom being a lighter sea-green. Her back bow has been reverted to the one from her original form but this time it's a light sea-green with narrow, long, sea-green ribbons extending from it down to her knees. Her boots are now knee-length with sea-green colored v-shaped borders with a yellow star in the center.

During the Silver Millennium, Sailor Neptune was also the Princess of her home planet and was among those given the duty of protecting the solar system from outside invasion. As Princess Neptune, she wore a sea-green gown with the symbol of Neptune on her forehead. She dwelt in Triton castle.


Elegant, sophisticated, though sometimes cold and capable of sharp anger, she has been described by Sailor Moon as 'the ideal princess'.

Michiru attends Mugen Academy with Haruka Tenou and the younger Hotaru Tomoe. She is patient and caring, almost always offering a smile or laughter to a situation. While polite and calm to a fault, she is not the most social person, but when she does become close with someone it is because she truly wants to. She dislikes being patronized and will not indulge others.

This can make her look like a snob, and her seeming perfection at everything does not help this perception of her. She is a genuinely intelligent young woman, a prodigal violinist, and an artist, already famous for her endeavors. Her intelligence is also apparent through her acceptance to Mugen Academy, a school with a very high acceptance threshold; only geniuses of some field are permitted enrolment.


Sailor Guardian Info

Michiru Kaiou can transform into Sailor Neptune by saying Neptune Planet Power, Make Up! Her attacks are centered around sea attributes.






Michiru Kaiou

In concept art, Naoko Takeuchi had planned for Michiru and Haruka to be affiliated with the Takarazuka Revue. Also, she was originally intended to wear a bow in her hair when at school. Neither characteristic was carried over to the final version of her development.

According to the Materials Collection, she had kindness "as great as the sea".

Sailor Neptune

Sailor Neptune's character was not developed until partway through the Sailor Moon series after the other Sailor Guardians had already been established. When she was created she was made along with Sailor Uranus, the pair was meant to be "complementary but opposite characters", and were meant to work along with Sailor Pluto from the beginning. Sailor Neptune's visual design is made to evoke images of her element, the ocean. The choice of her colors along with the wavy quality of her hair, which Takeuchi even joked, might be thought of as seaweed hair.



  • Michiru owns her helicopter that she calls the Kaio Maru.
  • Michiru is capable of using the Deep Aqua Mirror without needing to become Sailor Neptune.
  • Michiru's apartment number in the Infinity arc is "1306". If one removes the "1", they will get "306", the numbers of her birthday.
  • As with the other members of the Outer Senshi, her surname is also the name of a rail line in Tokyo.
  • The Sailor Moon "Materials Collection" confirms Haruka to be in her first year of high school at the start of her first appearance, along with Michiru.
  • At the 1998 San Diego International Comics Convention, Naoko Takeuchi confirmed that Uranus and Neptune were indeed intended to be seen as lovers. "Uranus has the heart of a man, while Neptune is more girlish," she said.[1][2]
    • The question "Are Uranus and Neptune lovers, and if so why did you make them gay?" came from a young female fan who wanted a clear answer. Naoko-san answered that "YES, they were a couple!"
    • Naoko further commented that Neptune was "feminine" and Uranus "masculine" and joked they had a relationship because "they had lots of time on their hands."
    • This relationship was changed in the 1st U.S. dub due to censorship.
  • In a 1996 interview with Animerica magazine, Naoko Takeuchi stated that while "Sailor Moon is closest to me in terms of personality; Sailor Neptune is the opposite."
  • Sailor Neptune's planetary symbol (♆) stands for the trident of the Greek and Roman god.
  • Sailor Neptune is one of the only Senshi (besides Sailor Mars) who possesses exceptionally strong psychic abilities and the only Outer Senshi who has such powers.
  • Sailor Neptune is the second Senshi to use a sound-based/supersonic attack (with her violin), the first being Sailor Moon with her supersonic wails.
    • She is also the second Senshi to use a personal/ordinary item in battle, the first being Sailor Mars with her ofuda.
  • Sailor Neptune and Sailor Uranus are the only members of the Sailor Senshi who's the backstory of becoming a Sailor Senshi had never been revealed in the manga.
  • Eternal Sailor Neptune is eliminated and given bracelets from Galaxia in the manga. But in the anime's fifth and last season, she voluntarily sells her own heart and soul to Galaxia and is given her mind-controlling bracelets.
  • Eternal Sailor Neptune is on the cover art of volume eight of the reprinted manga. On the kanzenban manga, Sailor Neptune appears on the cover of volume 6 along with Sailor Uranus.


Sailor Senshi

Solar System Sailor Senshi Sailor MoonSailor MercurySailor MarsSailor JupiterSailor Venus/Sailor V • Sailor Chibi MoonSailor PlutoSailor UranusSailor NeptuneSailor Saturn
Sailor Starlights Sailor Star FighterSailor Star HealerSailor Star Maker
Sailor Quartet Sailor VestaSailor PallasSailor JunoSailor Ceres
Other Sailor Senshi Sailor KakyuuSailor Chibi ChibiSailor Cosmos
Civilian Identities Usagi TsukinoAmi MizunoRei HinoMakoto KinoMinako AinoChibiusa TsukinoSetsuna MeiouHaruka TenouMichiru KaiouHotaru TomoeSeiya KouYaten KouTaiki KouPrincess KakyuuChibi Chibi
Allies Tuxedo MaskLunaArtemisDiana

Solar System Sailor Senshi Sailor MoonSailor MercurySailor MarsSailor JupiterSailor Venus / Sailor V
Other Sailor Senshi Sailor Luna
Civilian Identities Usagi TsukinoAmi MizunoRei HinoMakoto KinoMinako AinoLuna Tsukino
Allies Tuxedo MaskLunaArtemis