Hyuga

The Hyūga clan are descendents from the Ōtsutsuki clan, specifically from Hamura Ōtsutsuki's lineage. They are considered to be one of, if not currently, the most powerful clan. Their notoriety and prowess stretches far and wide, leading others to both praise and covet their abilities.The clan is separated into two parts, the Main House (宗家, Sōke) and the Branch House (分家, Bunke), a system that protects the secrets of the Byakugan from outsiders. The Main House runs the family while the Branch House protects it. The members of the Branch House are branded with a cursed seal upon the third birthday of the heir to the Main House. This seal gives the Main House members absolute control over the branch members, because they can destroy the branch members' brain cells with a simple hand seal, or cause them great pain to punish them. This seal also makes sure the secret of the Hyūga's Byakugan is safe, because it seals the Byakugan after the wearer. The current leader of this clan is Chiyoko Hyuga.

Byakugan

The Byakugan (白眼, Literally meaning: White Eye, Meaning (Viz): All Seeing White Eye) is the dōjutsu kekkei genkai of the Hyūga and Ōtsutsuki clans, inherited from Kaguya Ōtsutsuki. It is regarded as one of the Three Great Dōjutsu (三大瞳術, San Daidōjutsu, Literally meaning: Three Great Eye Techniques), the others being the Sharingan and the Rinnegan.Unlike other dōjutsu, the Byakugan seems to be available to its users from the time of their birth and does not need to be awakened through any means. Those who possess the Byakugan have very distinctive eyes: when the Byakugan is not active, they have enlarged and featureless white irides with no visible pupils; when the Byakugan is active, the pupils become more distinct and the veins near their temples bulge. Although the eyes of those with the Byakugan are supposed to be completely white, the anime depicts them with slight hints of lavender.

The Byakugan's abilities have left it highly coveted, evidenced by other villages' attempts to steal it; Kumogakure tried various machinations of obtaining a Byakugan during what was called the "Hyūga Affair". Ao of Kirigakure is the only foreign power known to have obtained a Byakugan from a Hyūga he defeated and he goes to great lengths to protect it; when Danzō Shimura, a loyal extremist of Konoha, finds out about this, he goes to similar lengths to retrieve or destroy it. Unlike other dōjutsu, transplanted Byakugan can be activated and deactivated at will. In order to reduce the probability of having their eyes fall into enemy hands, the Main House of the Hyūga place cursed seals onto the foreheads of Branch House members which, among other things, seal away the Byakugan upon their actual death.