TV-Series
Description
Michiru Kaiou, known in her transformed state as Sailor Neptune, is a character who first appears during the events surrounding the Infinity Academy and the emergence of the Death Busters. A young woman of sixteen, she is a student at the elite Infinity Academy, a school for gifted individuals, though her attendance there is primarily a cover for investigating the mysterious occurrences at the institution. She is a figure of immense artistic talent, celebrated as a violin virtuoso who performs her own concerts and also excels at painting, with her artwork being displayed in galleries. This profound connection to the arts is a defining aspect of her civilian identity, and her dream is to become a professional violinist.

In terms of personality, Michiru exudes an aura of elegance, sophistication, and a calm, polite demeanor. Her maturity and grace often lead others, particularly Usagi Tsukino, to see her as the image of an ideal princess. However, beneath this composed and delicate surface lies a more complex individual. She possesses a sharp intelligence and a refusal to be patronized, and she is capable of showing coldness or a sharp, intense anger when the situation demands it, especially when her mission is compromised. She has a subtle sense of humor, often using it to gently tease her partner, Haruka Tenou. A strong sense of duty underscores her actions, as she and Haruka have agreed on the gravity of their mission, which they believe may even require them to sacrifice one another if necessary.

Michiru's most significant relationship is with Haruka Tenou, Sailor Uranus. They are inseparable partners and lovers, a fact explicitly confirmed by the series creator. Together, they form a formidable team, with Michiru often acting as a calming and intuitive counterpart to Haruka's more direct and impulsive nature. The two live together and share a profound, unspoken understanding. Their relationship, depicted as a deep romantic partnership in the original Japanese version, was heavily altered in some older English adaptations, where they were incorrectly presented as cousins. Later in the series, after the rebirth of Hotaru Tomoe, Michiru, Haruka, and Setsuna Meiou (Sailor Pluto) live together to raise the infant Hotaru, forming a close-knit adoptive family.

As a Sailor Guardian, Sailor Neptune is one of the Outer Senshi, whose sacred duty is to protect the Solar System from threats that originate from beyond its borders. This mission sets her apart from the Inner Senshi, and she and Sailor Uranus initially operate independently, believing that the protection of their mission justifies a more ruthless approach, including the potential sacrifice of innocent lives to prevent a greater catastrophe. Her motivations are driven by this profound sense of responsibility, and she is fully dedicated to her role, often acting as a guardian of the "deep waters". Throughout the story arc, her role evolves from a distant, threatening figure to a trusted, if still somewhat reserved, ally to Sailor Moon, as they come to understand and respect each other's perspectives.

Sailor Neptune wields power over the deep seas and possesses several notable abilities. Even in her civilian form, Michiru has precognitive gifts, often sensing approaching evil by remarking that "the sea is stormy". Her primary transformation commands are "Neptune Planet Power, Make Up!" and later "Neptune Crystal Power, Make Up!" which allows her to become Super Sailor Neptune. Her signature attacks include Deep Submerge, where she unleashes a ball of watery energy, and Submarine Reflection, a powerful technique performed using her talisman, the Deep Aqua Mirror. This mirror, one of three legendary talismans, can reveal the truth, dispel illusions, and launch devastating energy blasts. In the manga, she also possesses a third attack, Submarine Violon Tide, which she performs using her beloved violin. Throughout her journey, she grows stronger, achieving a Super form and, in the manga, an Eternal form, though these power-ups are not always depicted on screen in the anime.