The Byakugan is a kekkei genkai dōjutsu of the Hyūga clan, inherited from the Ōtsutsuki clan. It is one of the Three Great Dōjutsu, alongside the Sharingan and the Rinnegan. Unlike the Sharingan, the Byakugan is present from birth. Its characteristic feature is completely white irises with no visible pupils. When activated, pupils become visible, and the enhanced blood flow causes the veins around the temples to bulge.
The field of vision covers nearly a full sphere around the user, with only a tiny blind spot above the first thoracic vertebra at the back. The gaze can penetrate virtually any obstacle — walls, earth, the bodies of living beings — allowing the user to see the chakra circulatory system with its 361 tenketsu. The range of vision increases with training: for Neji Hyūga, it ranged from 50 meters to over 800 meters; for Hinata Hyūga, it reached at least one kilometer and up to 10 kilometers. The Byakugan perceives chakra with a level of detail inaccessible to the Sharingan: it can distinguish between different types of clones, identify individual chakra signatures, and detect anomalies caused by genjutsu. This is the foundation of the unique Gentle Fist style — precise strikes to the tenketsu that seal or open the opponent's chakra flow.
Transplantation is possible: Ao of Kirigakure obtained a Byakugan from a defeated Hyūga and could freely activate and deactivate it. To prevent the enemy from capturing their eyes, all members of the Hyūga clan's branch family bear a cursed seal that destroys the Byakugan upon the user's death.
