Reicarnated as a Hyuga in the Warring States Period

Henji next morning gave him the decision of the Patriarch: "Hezel, the Patriarch has decided that it is your right to forgone the 3rd Elder position. But since you also want to enter the clan's library, if you make enough contributions to the clan you will have to bear the Caged Bird Curse Seal. Whether you succeed or not your sister will be the next 3rd Elder. Do you accept?"

Hezel's mom interrupted pleading: "Please reconsider. I don't want to lose you."

(Henji): "Hariko! We discussed it last night. It's his decision to make. So do you accept?"

Hezel: "Yes. Mother, please believe in me"

(Henji): "Fine. Take this token, you will be able to enter the clan's library."

A little building was guarded by two secondary branch ninjas, it was the clan's library. After showing the token, they let him through without problems. Inside there were a series of scrolls divided per type. There was a taijutsu, genjutsu, ninjutsu and even fuinjutsu section.

Surprisingly the most scarce section was the ninjutsu one. It had only seven jutsus: transformation, substitution, water wall, earth wall, body flicker, great breakthrough, and water needles.

The genjutsu section contained various methods to dispel illusions and cast illusions through the byakugan.

The taijutsu section contained diagrams of the tanketsu points, an explanation of what happens when you block certain tanketsu points, and the techniques derived from the Gentle Fist.

The fullest section was the fuinjutsu one. As you can see by the creation of the caged bird seal, the Hyūga clan is well-versed in the art of sealing. The reason is the fullest tough is not because it is the most researched subject but because fuinjutsu is a very broad one.

(Hezel): "Well, let's get started."

The first thing he did was to establish a work table for his next 3 years.

The things that he had to study to develop a new technique that could allow him to avoid the branding were quite a bit:

Tanketsu: He needed to familiarize himself with every one of the 361 tanketsu and study what happens when they are blocked.

Gentle fist: Now that he has unlocked the byakugan he can pass to the next part of the training. He will have to be able to hit the tanketsu with the chakra on his fingers, to block them at will.

Fuinjutsu: This is the most important thing and it will take away most of his time. This will be the focus of his next three years. His objective is to be able to form seals with his akra, like the Second and Fourth Hokage with the Flying Thunder God technique, and then fuse it with the Gentle Fist. Theoretically, this would allow someone to place seals in the opponent tanketsu.

Apart from these things he also couldn't slack off in his own development:

Physical conditioning: To have a larger chakra pool was necessary not only high spiritual energy but also a strong body. So his high-intensity daily training couldn't be put off.

Byakugan: Having opened his doujutsu, he now needed to develop it by feeding it chakra every day. The clan also had a series of exercises to improve its capabilities and to allow your brain to sustain its burden.

Meditation: It couldn't be skipped. Since the location of the three sage regions wasn't known, the development of a sage mode was entirely reliant on his efforts.

Tanketsu opening: To master the Eight Trigrams: Revolving Haven, the ultimate technique of the Hyūga Clan, it's necessary to open all the tanketsu of the human body. By doing so he would be able to expel chakra from every point of his body.

Chakra control: Gentle Fist, fuinjutsu, and in the future sage mode were all reliant on chakra control. So this is necessary to master. After all, sharpening the axe doesn't delay cutting the tree.