Haruka is a stubborn, protective individual, but is also strong-willed, capable, charming, and occasionally even doting.
Haruka is a racecar driver, even though she is barely sixteen years old when she appears. However, the timing of her birthday to the Japanese school year means she is one grade ahead of the Guardian Senshi.
Haruka is also extremely flirtatious and loves to tease pretty girls. In the manga, she even kisses Usagi. Throughout the manga, she is lightly flirting with Usagi, either out of habit from the first arc she appeared in or just for fun, and eventually Usagi would occasionally flirt back out of pure playfulness. Their relationship in the anime is different, as Haruka also refers to her as "Odango" or dumpling in the same way Tuxedo Mask does as a playful nickname. By the time she returns in Sailor Stars, however, she begins to refer to Usagi as "Kitten".
Although her relationship with Michiru is not implicitly sexual until later in the series, their romantic situation is referred to early on and generally understood by most of the metaseries' characters fairly quickly. It is sometimes a source of good natured humor, particularly because few of the other Senshi have serious romantic prospects in comparison and because the otherwise flirtatious Haruka finds it impolite to discuss romantic matters in public. In the anime, however, the physical aspects their relationship is limited to hand-holding, flirting and sometimes even humorous implying, but generally remains intact.
With her short hair and masculine hobbies, Haruka's character design is pointedly androgynous. On first meeting, most other characters think she is male. She further complicates the perception of her gender by appearing as a "Tuxedo Mask" instead of a Sailor Senshi in the first appearance. This form is never mentioned again.
Besides her relationship with Michiru, Haruka is also close friends with Setsuna, because the three of them work closely together as Outer Senshi. Following the destruction of the Death Busters and the rebirth of Sailor Saturn as an infant, they vow to be her family and care for her. Later story arcs show that the four live together happily for some time. Nothing about Haruka's family life is ever discussed, although she and Michiru Kaioh appear noticeably wealthy by unknown means. In the manga, Haruka says that she and Michiru have "wealthy patrons."
The anime and manga versions of the character are reasonably interchangeable, although her standoffishness is more pronounced in the anime. Like Michiru, Haruka is sometimes considered colder and almost unfeeling.
Haruka's greatest dream, prior to becoming a Sailor Senshi, was to be a professional racer. Thereafter it is still a well-loved hobby, and driving is listed in the manga as her best skill. She is also a skilled runner, belonging to the track-and-field club at school. On occasion, Haruka can be seen playing piano in accompaniment during Michiru's violin performances. While Physical Education is her best class, Modern Japanese is her worst. Haruka is highly private, able to tease others while becoming flustered if teased herself, and has difficulty with confessions. Her favorite food is salad, and her least favorite is natto (fermented soybeans); she also likes the color gold. According to Michiru, Haruka has had trouble with popular men on more than one occasion. Haruka denies this, but it clearly annoys her.
As of recent Haruka and Michiru have broken up due to differences of opinion. Weather or not they will get back together is still unknown, it seems there is another coming into the picture.
Stay tuned for more information.