Naruto world reincarnation

Saito after falling unconscious was having dreams about his old life, he was back to his family living his daily life, the same old life he left behind, but the sweet dream soon turned into a nightmare with all his family members and loved ones killed one after the other, when he confronted the perpetrator it was none other than himself. And just as his malefic reflection was about to strangle him to death he woke up. His body was covered with cold sweat, his hands where shaking the visions of his family dying by his hand. But he soon calmed down that was just a dream.

He started checking out his body condition, he started trying his chakra control exercise. But as soon as he started moving his chakra he felt a certain anomaly, his chakra was somehow tainted by a foreign chakra wish could only be the Biju chakra.

Unlike normal Jinchuriki, Saito wasn't exposed t Biju chakra from a young age, and even those who were exposed to it later in life didn't directly absorb a huge chunk of foreign chakra into their bodies, Saito knew that for the moment he should try stopping the chakra from seeping into his own chakra reserves. So he called Karin over to help reinforce the seal.

Karin was shocked after checking the seal, the chakra was actually slowly corroding the seal, normally that seal should be strong enough to lock the chakra, even if it was stronger it shouldn't have been able to break the seal so for now she put a multi layered seal and gave Saito the way to unlock them. It didn't take much time after that for him to recover his control and he even managed to raise it to the next level, he found out that the Biju chakra he absorbed wasn't pure but was mixed with wood element chakra, wish explains why the seal was corroded, the wood nature chakra has an amazing property to absorb and weaken other chakra natures so when the seal came into contact with the seal it started absorbing the chakra that maintained the lock and even now the chakra was slowly breaking the seals so Saito had to find a solution, and after numerous tests he finally found out a solution, by using the absorbed natural chakra he could slowly repress the rampaging Biju chakra and slowly turn it into his own, but in order to fully counter the wood element chakra he should use multiple natural chakras at the same time, he knew that it was dangerous to mix the elements without proper preparation but he was out of options.

While Saito was deep in his laboratory researching the sharingan. Jugo, Suigetsu and Fu where out of the village following a lead they found about the legendary swords. They did inform Saito, before leaving, who offered to go with them only to be rejected. The others knew that he only wanted to protect them but they wanted him to learn that they could handle themselves and that they can stand beside him as comrades. Saito had to give up, because he knew that he won't be always present, and that his companions where right about him trying to shield them, but he still had them take a communication seal just in case they were in trouble. So he went back to his research and training while Karin on her own right was learning from Tsunade and improving her Fuinjutsu.

The days became weeks and Saito was getting closer to reach a breakthrough in his research, he also managed to learn the two last sage modes, fire and wind. The fire sage mode made him able to increase the explosive power of his fire jutsus enabling him to create white colored flames that consumed everything they touched, he also could create an invisible natural chakra coat making him able to misdirect his opponents.