Kaoru Hitachiin is one of the main characters from the Ouran High School Host Club anime and manga.
Kaoru is the younger of the Hitachiin twins and is in Class 1-A with his older twin, Hikaru; and fellow Host Clubmember, Haruhi Fujioka. Despite being younger than his brother, Hikaru, he is shown to be much more mature and level-headed.
In the AWA fics, Kaoru is a student at the AWA Academy.
When not in uniform, Kaoru likes to wear somewhat outlandish designer clothing, but fortunately, almost always wears clothes of different style or different than color than his twin, Hikaru. In the manga, he has short, somewhat messy auburn hair. Kaoru has also dyed his hair powder blue, and later pink, to confuse the Host Club and their guests, though Haruhi still manages to tell the Hitachiin twins apart.
When facing them, Kaoru's parts his hair to the left side, while Hikaru's parts his to the right; when they stand together Kaoru is usually on the left with Hikaru on the right. Although they tell Tamaki that they switch it on a daily basis, the parting of their hair is generally consistent, unless they are deliberately attempting to confuse others. Both twins possess amber-colored eyes, a thin face and pale skin.
Kaoru Hitachiin is the younger of the Hitachiin identical twins. He and his older twin, Hikaru, are introduced when Haruhi Fujioka stumbles upon the Host Club. Being in the same class as Haruhi, they serve as major rivals against Tamaki for Haruhi's romantic attention. Kaoru is just as playful as his elder brother, but is also a more insightful and easy-going person. He is also the first of the two to understand that their co-dependence must end, if they are to develop into separate and whole individuals.
As members of the Host Club, Kaoru and Hikaru are the "Little Devil" types, as they are mischievous (but not malevolent) troublemakers. They are famous for their "Forbidden Brotherly Love" package, carrying out twincestuous schticks for the entertainment of their female customers. A favorite game of theirs is the "Which One Is Hikaru? Game," in which they cover their hair with matching caps and ask people to identify Hikaru. No one except for Haruhi has guessed correctly, with logical reasons for doing so. Due to this, and the fact that she sees them as unique individuals, both brothers develop romantic feelings for her. Though each brother takes her on a date, only Hikaru's is shown in Ep 16 - Operation Haruhi and Hikaru's First Date!
Kaoru and Hikaru are both wealthy and playful; however, Kaoru is the calmer and more mature of the two. When apart from his elder brother, Kaoru becomes a pleasant person, acting in a selfless and serious manner; but when he is with his elder twin, he reverts to being a scamp-like individual. Although the twins have spent the majority of their lives interacting only with one another, Kaoru demonstrates an understanding about social interactions and innate self-control.
Kaoru is born under the star-sign of Gemini, the Twins. The positive traits of this sign are adaptability, versatility, enthusiasm, eloquence, wit and intellectualism; the negative traits being inconsistency, superficiality, indecisiveness, lack of focus and nervousness. There is speculation about whether Hikaru and Kaoru each possess all traits or if the traits are split between them to create a "good" twin and an "evil" twin.
Both of the twins refer to Tamaki as "Boss" in the English version and as "Sir" in the Japanese version.
Kaoru is a high flying fighter and incorporates a lot of hard striking attacks into his arsenal. Kaoru favors a northern lights suplex and a running corkscrew elbow and like Hikaru, he packs a mean superkick.
- In the AWA fics, Kaoru, alongside his brother Hikaru, are known as The Hitachiins.
- Kaoru along with the rest of the Host Club are the first characters from Ouran High School Host Club to be introduced in the AWA fics.
- The manga and anime depict Hikaru and Kaoru's relationship as two plants growing from a single seed. Later, in recognition of their increasing individuation, two huge flowers of identical type bloom in different colors.
- Kaoru often turns to Honey for advice after an upset with Hikaru, whereas his twin seeks comfort from Mori.
- The Hitachiin twins share the same birthday as the Kurusu twins (from Uta no Prince-Sama).
- Like the other Hosts, Kaoru's phone matches his rose color, which is coral pink/orange.
- After Hikaru dyes his hair in the manga, the visible differences between the twins increase. Hikaru starts to wear clothing with bolder patterns while Kaoru opts for more classic outfits and, in the chapter title pages, Hikaru is usually drawn with angry eyebrows and an open mouth while Kaoru maintains a calm smile.
- Both Kaoru and Hikaru are right-handed.
- Kaoru is said to be 10% less evil than Hikaru.
- It is revealed in "This Is Our Ouran Fair" that Hikaru is a talented equestrian, having driven the Host Club throughout the school campus in a horse-drawn carriage.