The Byakugan – White Eye – is the kekkei genkai of Hyuuga Clan that has been passed down the generations of their clan for around a thousand years. It was inherited from their ancestor, Otsutsuki Hamura, who was born with these eyes due to his mother consuming the fruit of the God Tree. It is known as one of the Three Great Doujutsu alongside the Sharingan and the Rinnegan.

Almost everyone in this bloodline has white irises and pupils and can potentially awaken the Byakugan once they have the necessary chakra capacity and control. Whenever the Byakugan is activated, the veins around the eyes swell from the increased flow of chakra.

Because actually activating the eyes is quite difficult, the Hyuuga developed a hand-seal sequence to channel their chakra in the correct way which is taught to all of their children. Experience and skill allows them to skip most or all of these steps but even experienced Hyuuga are in the habit of using at least one hand seal to make it easier.

When active, the eyes gain a supernatural acuity that allows them to see the world with incredible clarity. Everything becomes that much sharper, distances are easier to perceive, colour is more pronounced and their minds can process everything they see at a faster rate than normal. They can even see in low light conditions as clear as in day and can adapt to the most intense levels of light as well. This perceptiveness makes it an ideal tool for analyzing a person’s mental state through their body language and using that knowledge against them.

One ability that the Byakugan shares with all other doujutsu is seeing chakra as a part of the visible spectrum. Ordinary eyes are only able to see chakra when it’s concentrated to the highest levels but the Byakugan can see it in even the faintest quantities. It perceives chakra as different colours which are unique to each individual, judges chakra levels, reveals things hidden by chakra from the naked eye, shows disturbances in a person’s chakra flow such as genjutsu and sees it in the jutsu used against them.

The Byakugan possesses panoramic vision which allows the Hyuuga to see in almost a full 360° degrees so that they can view practically everything around them. By doing so they are able to anticipate attacks from any direction, including directly above them, with greater awareness than those who would rely on their other senses to compensate. However it does have a blind spot where attacks are able reach the Hyuuga without them seeing it beforehand.

They are capable of telescopic vision which can see over dozens of meters further from their earliest activation, and which can be trained to extend hundreds of meters and even tens of thousands of meters. Such range means that they can spot enemies and track their movements with them none the wiser.

And lastly they possess x-ray vision which allows them to see through physical objects as if they were not there to view whatever may exists beyond them. This ability in particular makes hiding from the Byakugan so difficult as it can see through solid walls, smoke and dust, clothing and equipment or even through a person’s flesh to see their bones or internal organs.

It also assists in their ability to psychoanalyze their opponents as they can see how their body reacts such as producing more sweat, increasing their heart rate and other chemical changes. As such, very few people are capable of lying to a Hyuuga.

The ability to see through the ground is particularly useful for scoping out enemies moving underground but difficult to maintain given the sheer disorientation in not being able to see the ground. It can also struggle with certain types of barrier ninjutsu which can be difficult to see through due to the makeup of chakra that composes them, making them one of the most effective defences against the all-seeing eyes.

Individually, these are all incredibly useful abilities but they are even more powerful when used together.

The Hyuuga combine their x-ray vision with their ability to see chakra, allowing them to see the chakra pathways within the human body. This served as the foundation of their Gentle Fist as they inject their chakra into the enemy’s pathways that are entwined with their internal organs to damage them in ways they can’t defend against.

Those with higher than average visual acuity – naturally or trained – can even see the 361 chakra points which release chakra from the body which can then be targeted to disrupt the enemy’s chakra flow. Viewing the chakra pathways directly means that they can literally see the enemy generate chakra, transform it into a jutsu and channel it through their body, allowing them to react to an attack before it is actually unleashed.

It is even one of the reasons why the Hyuuga are so gifted with chakra control. Where other people can only rely on how their chakra feels as they manipulate it, those with the Byakugan can actually see the chakra moving through their own body. With this knowledge, they can better adjust their chakra levels when applying it to exercises or jutsu to use exactly as much as they need.

And they combine their panoramic vision with their telescopic vision to see as far as possible in 360 degrees so that they can perceive everything happening in that territory and defend themselves against it. It is perfect for fighting against multiple enemies at different ranges as they are able to keep track of any attack against them where other ninja would be overwhelmed.

If the Hyuuga truly pushes their visual processing power then they can experience a phenonema where time appears to slow down so that they can perfectly perceive everything around them and respond.

However using multiple types of vision can limit their maximum ability such as when trying to extend their visual range while looking in 360 degrees at the same time; they cannot see nearly as far as they would by just focusing on their telescopic vision. This is why they usually focus on a specific type of vision and then, as the circumstances change, switch over to a different type of vision to adapt, often assisting that change with a hand-seal.

Different Hyuuga have different strengths and weaknesses when it comes to their Byakugan just as regular people do not have always equal eyesight. Hyuuga Hinata’s is particularly proficient in its telescopic vision which could see roughly a kilometre away when she was rookie genin which increased to seeing at least ten kilometres and then twenty kilometres as she grew older. Her cousin Neji couldn’t match her maximum range yet his eyes were naturally better at seeing minor details at close range which is why he could see chakra points at such a young age unlike her which was combined with his prodigious talent for the Hyuuga’s Gentle Fist.

Overusing the Byakugan by maintaining its active state for hours on end, especially while pushing its eyesight to the limit, can strain the eyes to the extent that they temporarily damage their vision. Even if the Hyuuga keeps their Byakugan active, they would normally leave it in its default state and then change its type of vision when needed.