Konoha village
It have been two week since the start of our training under Uchiha Mark. It can be said Mark is a indeed an elite jonin. Only after a week's training i can already utilise all my strength in the battle.
After second week of training i can effectivly use thundar cloak method and Thundar breathing sword technique simultaneouly during the battle.
Mark fights against us, most of the time Me and Nami but sometimes Tatsu joins too. He fights with us till we are exhausted and unable to move. Then He will let us rest for an hour and during that time he will tell us about mistakes made by us during battle and his experience in war.
Along with Nami i too have learned some illusions. Mark also thought me Sharingan practice method. Its the method that is only thought by an elite jonin to the person who have newly awakened their sharingan. It can only be taught person to person. Recording it in scrolls is absolutly forbidden by the clan. When a clan member awakens his or her Sharingan, his/her brain unconsiously start to produce Yin-Chakra. After years of practise and experimenting Uchiha ancestors found a way to consiously control the production of Yin-Chakra.
After a person gets proficient in this technique his/her control and power of sharingan increase two-fold. Long term practice can also lead to increase in quality of Yin-chakra produced which basically leads to increase in tomoe's of ones sharingan.
Usefulness of this method is to those who have awakened sharingan. For those who have not awakened sharingan, even if use this technique for 10 to 20 years they will still not awake their sharingan or control Yin-chakra secretion.
According to various data recorded by Uchiha Ancestors, an uchiha can awaken his/her sharingan when he is 11 years old to 20 years old and 22 years old is maximum because after this age probability of awakening of sharingan reaches 1 or 2 percent. It is recorded that puberty starts for ninjas around 11 year of age and lasts till 22 years of age. This is golden period for practice for ninjas. For Uchiha's, during this growth period if an uchiha brain is stimulated, it will easily start to produce Yin-chakra. When a body reaches 20 years of age, body organs at this age stops growing and reaches their peak and an persons emotion stablize at this age. So its difficult for brain to be stimulated and further awkening of sharingan. So its best to awaken Sharingan during the golden time period of body i.e 11 to 22 years of age.
If an uchiha have two tomoe sharingan at 22 years of age it is basically impossible for him/her to have three tomoe sharingan in his life unless stimulation he/her is crazy strong.
This technique can only be practised till Three tomoe sharingan because to upgrade a sharingan to Two tomoe we need thrice the yin-chakra quality, for Three tomoe sharingan we need nine times Yin-chakra quality. But to upgrade from Three tomoe sharingan to above we need thirty times the Yin-chakra quality. Which is nearly impossible because if there are no accidents, it take about 2 to 3 years to increase yin-chakra quality to awaken two tomoe and later it take 4-5 years to increase Yin-chakra quality for awakening three tomoe sharingan. For an uchiha to increase his/her Yin-chakra quality to thirty time it will take around 20 to 30 years.
Considering on average an uchiha awakens his/her sharingan at 12-15 years of age. Lets take 12 years as base and lets guess conservatively if her/she is genious . So If an uchiha awaken sharingan at 12 years of age, so he/she will awaken two tomoe at 14 or 15 years of age. After that three tomoe will awaken around 18 or 19 years of age. Which leaves 2 to 3 years of golden age of growth. There is not enough time for an uchiha to increase his/her Yin-chakra quality thirty times to evolve his/her sharingan after three tomoe's. So for Sharingan to evolve after Three tomoe is basically an impossible probability unless an miracle happens.
So in the clan, if an Uchiha awakens his/her sharingan before the age of 14 are called genius. And all those after this an average uchiha.
So my sister who awakened Three Tome Sharingan at 12 years of age is absolute genius. She is hope of the clan to evolve Sharingan after Three Tomoe's. Her having three tomoe sharigan is absolute secret of the clan. Except for me, only one to know about her sharingan are a few clan elders and clan leader. Even elite jonin are not qualified to know about it.