Reborn In Naruto World

Tenno was a transmigrator in the Naruto world. He was 6 years old, but in order to become a ninja, all his free time was spent on cultivation and he had to work hard to increase his strength. 
In his new family, he had a sister, who liked cooking, but their parents were civilians, so he had no possibility to access Ninjutsu or Secret Arts scrolls directly.
 But their parents had a lot of business with ninjas, so he had the chance to cultivate. 
After reaching the level of sensing and extracting the chakra, a way to use energy in this world, his Divine level forging system was activated. Firstly he forged a particular Kunai, with the ability to create a physical clone when infused with chakra, and this clone was a full clone, not merely an illusion technique. 
After this, he forged other Kunais, with different rates of success, and he treated this method as a way to temper his body. 
He gave some of these kunais to his sister to keep her a better way of practicing her skills.
After this, both the siblings prepared to go to the Ninja school to test themselves, join the school, and have a proper and direct way to improve and become a pure Ninja.