Reincarnation into the World of Naruto

Junichiro called Jiro over a couple of days after the fifth birthday of the twins and locked eyes with him, emanating an aura of utter seriousness.

"Jiro, you know that that it has been six years since the Nidaime, Tobirama Senju, was slain by the Kinkaku force sent by Kumogakure right after a peace treaty was signed to end the first Shinobi War right?"

Jiro nodded in response.

"I do not know how long peace is going to last. I'm too busy with the newly established police force to help train your brother and your mother is too kind to actually use force against your brother. And the elders just send henchman like Jin to treat the heir delicately so their help is useless. I know that you have no qualms with treating your brother roughly so teach him how to fight"

Jiro had a pensive mood about him before shaking his head in disagreement.

"I do not have time to teach Fugaku because I am trying an important experiment. Furthermore father, wars do not get waged right after an earlier one because everyone is trying to recover from the war. New wars get waged by new generations."

Junichiro gained a look of thoughtfulness over his face, but he decided that Jiro could make time to train his brother as well as experiment if he was given some enticement.

"Jiro, if you agree to train your brother, I will agree to help you in your experiment as well as teach you the shadow clone justsu. The shadow clone justsu is a jutsu that produces a corporeal clone of you which you can use to experiment safely as well as gain experiences more quickly. However, you must promise to use only one at a time until your reserves are more built up."

Jiro agreed with an eager gleam in his eye.

Akane was watching the "training" session conducted by Jiro with Fugaku and she was not eager to spectate how Fugaku was fairing against his brother.

Fugaku shakily took a breath in and stared at his brother while formulating a plan to take him down. Trying to beat Jiro with the academy style of Taijutsu proved to be useless because Jiro stuck too close for him to try and attack with a balanced style. Fugaku shifted into his stance for the Uchiha Taijustsu style and locked eyes with his brother while giving a nod to indicate for the match to begin.

Jiro dashed forward and launched a quick punch which Fugaku dodged. He followed up with a straight punch, but Jiro used his close distance to grab a hold of Fugaku's wrist and drag him forward to throw him off balance. Jiro then used his other hand to slam a fist into Fugaku's gut sending him sprawling backwards with a pained look over his face. Jiro stuck a hand down for Fugaku to grab and explained:

Fugaku took the opportunity available to him while his brother was explaining to try and pull Jiro down, but Jiro simply fell with the pull and jammed his elbow into the gut of Fugaku making him cough up saliva.

"This match is over brother, you lost."

Junichiro sighed in wonder at the idea that Jiro came up with. It is common knowledge that tiny tears in muscles are formed after working out and after those muscles get healed over a period of time, they get stronger. Unfortunately, Medical Chakra while healing the muscles, does not let them improve. Jiro came up with the idea of using only Yang Chakra to not heal the muscles or speed up the recovery process, but to create tears in the muscles. Yang Chakra tends to be more overbearing than Yin Chakra so it is more physically damaging while Yin Chakra is more spiritually damaging.

The premise is to flood the muscle that you want tears in with a very large amount of Yang Chakra and then move the Chakra within the muscles with a rotational speed your body is not used to so your muscles end up gaining tiny tears.

Jiro and Junichiro found the newly formed body refining technique to have some unfortunate flaws with it. The Chakra provided has to be from the same person getting their muscles torn because the body naturally prevents permanent damage if Chakra is from the same person. If it was from some other person, their Chakra could end up seriously damaging the muscles of the other person.

Another flaw is the pain that accompanies the process of refining. Artificial damage is still damage, but the damage is happening over a much shorter period of time so the feeling of tearing one's muscles is multiplied by the speed of the Chakra rotation as well as how long the technique is applied. Unfortunately, a recovery time of a couple days is also required for the body to fully heal from the damage done by the technique.

The only, but very important merit to this technique was it's ability to save time on a very large level. What might take a week or more of harsh training could easily be done in minutes with the price of pain which could easily be withstood. Sadly, the recovery time would leave the body unable to practice the technique again for a couple of days.

Junichiro quickly called a council meeting with the Uchiha elders and other important members after he discussed the flaws and merits to the body refining technique with Jiro. As much as he loathed to have a discussion with the elders, they only wanted the best for the clan. Junichiro knew as well as the elders that the Nidaime of Konoha did not have any positive feelings for the Uchiha and purposefully left them to be the police which served to isolate them from the rest of the village.

Junichiro was also fully aware that this technique could be shared with the village or several select clans to drastically improve the relations between the Uchiha and whomever the technique was shared with. A decision this important would require not only elders, but also other important members of the clan.