Hyuuga - Byakkugan
Konoha Village's second founding family is the Hyuuga clan. Also a "noble" family (that is, a long, age-old family) their
Advanced Bloodline is also a DouJutsu, the Byakugan. Unlike the Sharingan, which only appears to a few select members of the Uchiha clan, Hyuuga's eye technique is inherited by every member of the family, although it is stronger in some than others. Translated directly to White Eyes, its name comes from the odd, pale eyes that members of the Hyuuga clan inherit, giving them an almost intimidating look.
The Hyuuga clan has a very long history that dates back to the beginning of Hidden Leaf Village, and that history is plagued with pain and discrimination. The clan itself is split into two Houses - the Main House, who carry the bloodline to its maximum potential and are taught all of the clan techniques, and the Branch House, who exist only to protect and serve the Main House. They are denied the higher level training of the Hyuuga unique techniques, such as Hakkeshou Kaiten (Divination Whirl), and are forever enslaved to the Main House.
The method of sorting new born children into each house is simple - those born first from a Main House member become Main House while those born after become Branch House members. Any children of Branch House members remain within the Branch House. In order to secure this enslavement every Branch House member has a special Cursed Seal engraved into their forehead from the age of four, representing a caged bird. It is a reminder to the Branch House of their duty to the Main House and a leash of sorts. With simple hand seal, any Main House member can inflict a huge amount of pain to a Branch House member, killing the victim's brain cells and hurting their optic nerves. Needless to say, death is easy to cause and after the victim's life ends, the seal recedes and destroys their optic nerves, sealing the Byakugan and preventing any other shinobi from examining the corpse and finding the bloodline secrets. Because of this Main House members do not usually go on missions and are taught most of their technique at their home, as well as the methods of running the family. Exceptions are made, however, especially if a Main House heir is considered weak by the family Head. Hyuuga Hinata, for example, is not considered a worthy heir to Hyuuga by her father (although she still remains the family heir) and he did not care what became of her. All of this strife has caused a huge rift to appear between the two Houses, and many Branch House members are bitter and resentful of the Main House.
The Hyuuga claim themselves to be the strongest in Konoha, and with only one Uchiha member left in the village this may be true. However, if the Uchiha were at their prime it's doubtful whether this claim would stand. Kakashi does say that the Byakugan is slightly stronger, but with the three unique Sharingan techniques that is a doubtful statement.
Nevertheless, the Byakugan is something to be feared. Like the Sharingan, the Hyuuga member only needs to channel a little chakra to the eyes to activate the technique, the enhancement made clear with bulging veins around, and even inside, the eye. Also, since it is a DouJutsu, it can identify and penetrate any TaiJutsu, GenJutsu or NinJutsu. However, the similarites with the Sharingan end there. The enhancement also grants the user 360 degree vision meaning he or she can see all their surroundings in perfect detail. Any attack within fifty metres is detected so the user is essentially impossible to sneak up on while it is active. However, this insight can be focused in different ways. If the user wishes, he can see several miles ahead by focusing his eyes to the front, or he can see through any person or obstacle with ease. When facing a person he can penetrate his skin and see the chakra circulatory system, with the chakra centre and all 361 tenketsu (chakra openings) on the surface of the skin. On its own this may seem impressive, but doesn't sound like it could be useful in combat. However, the Hyuuga have devised their own devastating TaiJutsu style, called Jyuuken (Gentle Fist).
The Hyuuga seem to also inherit an amazing amount of chakra control. Their combat style focuses on chakra manipulation, of their own and the opponent's. Unlike Gouken (Iron Fist) which attacks the surface of the body, breaking bones and such, Jyuuken attacks an opponent's internal organs and chakra circulatory system. Since there is no way to train your internal organs the damage caused is almost always lethal, no matter what your strength or toughness. This is the key to Jyuuken and why it is feared so much. The user basically attacks the opponent with graceful palm strikes and releases a burst of chakra from their tenketsu in their hand every time a strike connects, shoving chakra straight into the enemy's body. As the Byakugan can see the chakra system they can go for the chakra centre directly, causing great pain and anguish to the opponent, or they can attack the critical organs. The chakra circulatory system is closely intertwined with the inner organs that mold chakra, so attacking the system does damage to the organs themselves. The final and most frightening aspect of the Byakugan and Jyuuken is it allows the user to seal an opponent's tenketsu, preventing them from molding chakra or, in the case of a Hyuuga opponent, preventing the use of Jyuuken. Using just their fingertips, the user hits the tenketsu with pinpoint accuracy and seals it with a small burst of chakra.