After Mizuki returned, Riyue could once again go to her house every day for a free meal. Mizuki also decided to train Riyue, teaching him the Gentle Fist and how to use the Byakugan.
As someone who knew the Naruto story well, Riyue knew the Byakugan was the Kekkei Genkai of the Hyuga Clan. It originated with Kaguya Otsutsuki, the mother of the Sage of Six Paths. Her younger son, Hamura Otsutsuki, inherited her Byakugan. Later, Hamura became the head of the Otsutsuki Clan and took his entire family to the moon. The Hyuga Clan were his descendants who remained on Earth, inheriting his Sage Eye—the Byakugan. Unfortunately, they did not inherit his Sage Body.
The Byakugan had astonishing insight and could see objects from more than a kilometer away. It also gave its user a 360-degree field of vision with no blind spots. The Main Family's Byakugan could see all the space around them, but the Branch Family's Byakugan had a blind spot because of the Caged Bird Seal: a one-degree blind spot that spread outward from directly behind the first thoracic vertebra.
The Byakugan also had powerful penetrating vision. Its user could see a target's chakra pathways and the flow of their chakra, allowing them to gauge how much chakra the target had, predict what jutsu they might use, and even tell whose chakra it was.
Another advantage of the Byakugan was how easy it was to awaken. Any Hyuga ninja could awaken it. In addition, members of the Hyuga Clan who possessed the Byakugan could release chakra from any tenketsu in their bodies, something ordinary ninja could not do.
Of course, the Byakugan's advantages only mattered against ordinary ninja. Since chakra did not belong to any of the five basic natures, members of the Hyuga Clan could not use the five elemental styles. Against a skilled opponent, the Byakugan offered little advantage even if they lacked a Kekkei Genkai. Just look at the Hidden Mist's Water Style, the Uchiha Clan's Fire Style, the Hidden Cloud's Lightning Release, Iwagakure's Earth Style, the Hidden Sand's Wind Release, and all the other abilities that kept cropping up. Every one of them could give a Byakugan user a headache. Hyuga ninja had mostly been reduced to supporting their teams with reconnaissance.
"Riyue, to activate your Byakugan, you first need to send chakra through your network of pathways and into your eyes. Like this." Mizuki formed several Hand Seals in front of her chest. "Byakugan!" A surge of energy spread outward from the center of her brow. Her eyes turned a pale blue-white, veins bulged beside them, and a ring of black markings and several patterns appeared in her pupils. Everything in her field of vision came into view.
The cataract eyes really aren't very attractive, Riyue thought.
Mizuki stopped channeling chakra, and her eyes returned to normal. "Once you're skilled at using the Byakugan, you'll be able to activate it without Hand Seals. Like this." The veins beside her eyes bulged again as chakra surged into her Byakugan, and the black patterns reappeared in her pupils.
Then Mizuki explained the Hand Seals needed to activate it, which pathways and tenketsu to use to channel chakra to the eyes, how much chakra to use, and a few things to keep in mind.
Following Mizuki's instructions, Riyue began forming Hand Seals and channeling chakra into his eyes.
"Byakugan!" Riyue immediately felt the veins beside his eyes bulge, and a surge of energy spread outward. Everything around him looked different. The world had become black-and-white and transparent. Without turning his head, he could see what was behind him, the chakra flowing through Mizuki's body, and the flowers and grass behind his sister. His vision could pierce through layers of trees and make out tiny objects.
Riyue found that he could see everything clearly within a hundred meters. Not even the slightest movement of the grass escaped his notice. By concentrating a little, he could make out the patterns on a distant tree as clearly as if he were standing right in front of it. Beyond a hundred meters, things became less distinct; he could no longer see details on a microscopic level or see through objects. The farther away things were, the fewer details he could make out, and the blurrier they became. Beyond five hundred meters, his vision felt like an ordinary field of view.
It looks like my Byakugan's effective range is a hundred meters right now, and I can barely use it out to five hundred. That means I can see more clearly than ordinary people within five hundred meters, but it doesn't do much beyond that. It's like I have a pair of see-through binoculars and a magnifying glass that can see a hundred meters, plus a telescope that can see five hundred. I need to train my Byakugan properly. One day, I want to see things beyond an ordinary person's range.
"Hmm! This feels pretty good. I've practiced chakra control for a long time. Let's see if I can activate it without Hand Seals." Riyue deactivated the Byakugan.
Then Riyue tried to control the flow of his chakra, slowly sending it into his Byakugan without forming Hand Seals. The veins at the corners of his eyes bulged again, and the Byakugan activated.
"Riyue, you activated your Byakugan without Hand Seals?" Mizuki stared at him, stunned.
"Yeah, Mizuki. It's still a little difficult." Riyue smiled and nodded.
"Other people have to practice for a long time before they can activate the Byakugan without Hand Seals, but you can already do it..." Riyue's talent amazed Mizuki.
"Uh? I guess so. Is it really that hard to activate the Byakugan without Hand Seals?" Riyue asked.
Mizuki nodded. "It took me half a year of practice before I could do it without Hand Seals. Riyue, could you really be a genius?"
"Uh... It's not that impressive. I've just practiced chakra control a lot." Riyue scratched his head sheepishly.
Just then, Riyue's Byakugan shut off on its own, and his eyes returned to normal.
"Hm? What's going on?" Only then did Riyue realize that his chakra was almost completely gone.
Riyue was taken aback. Th-this Byakugan uses way too much chakra! I only used it for five minutes and did nothing else, yet my chakra's gone! How do Neji and Hinata fight with their Byakugan activated? Isn't using the Byakugan supposed to take very little chakra?
"Riyue, how is it? Have you gotten used to the Byakugan?" Mizuki asked, looking at him.
"Mizuki, does the Byakugan use a lot of chakra?" Riyue couldn't help asking.
"No. The Byakugan uses very little chakra. A Genin can keep it activated for at least an hour, and a Chunin can use it continuously for four or five hours without any problems. Jonin can keep it activated for a long time. Sometimes, when they have to travel and scout, Hyuga Jonin keep their Byakugan on as they go, only turning it off when they rest. Otherwise, how could they use it in battle?" Mizuki looked puzzled.
"Then why does my Byakugan use so much chakra? It was gone after only five minutes." Riyue was immediately frustrated.
Mizuki activated her own Byakugan and said, "Maybe you're channeling too much chakra. Activate yours again so I can take a look."
After waiting for his chakra to recover to two-thirds, Riyue activated the Byakugan again. Mizuki studied his eyes closely, looking thoughtful. In less than three minutes, Riyue's chakra was gone again.
"Your chakra control is good, and the amount you're channeling is fine. It's just being used up so quickly. It's practically gone as soon as it enters your eyes." Mizuki spoke after examining him carefully.
"Then what's going on?" Riyue felt miserable.
"I haven't seen anything like this before, but I know of something similar. The Main Family's bloodline is much purer than the Branch Family's, and their Byakugan is called the Pure Byakugan. Long ago, they were even called the princesses and princes of the Byakugan. Their Byakugan is stronger than that of ordinary Branch Family members, and it uses less chakra than ours. But Riyue, your Byakugan is using far too much chakra. This is the first time I've seen anything like it..." Mizuki said after thinking it over.
The princess of the Byakugan? I guess they called them that back in the Otsutsuki era. I remember Otsutsuki Toneri calling Hinata that because of her Pure Byakugan... Riyue pondered.
Could my Byakugan be too impure? Does bloodline really make that much difference?
After resting for a while, Riyue activated his Byakugan again. He carefully examined what was happening inside his body. He saw the chakra near his abdomen rushing along his pathways toward his eyes. It was being consumed at an astonishing rate. The Byakugan was like an insatiable monster, rapidly draining his chakra.
Then Riyue took a closer look at Mizuki. The chakra flowing through her Byakugan moved much more slowly. He carefully compared the two of them, then examined their Byakugan, pathways, tenketsu, lower abdomens, and chakra flow, searching for the reason his chakra was being used up so quickly. Finally, Riyue spotted a difference.
"Huh? Why is it like that?!" Riyue was shocked.
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