Naruto: Rebirth with Rinnegan

A med student named Fred dies in his sleep and is Reincarnated into the body of a child in the Naruto world.

After many years of constant hard work and training, he develops a special solution capable of increasing his Yang half to match his yin half, the results are unprecedented to him.

At the Age of 15, after 8 years of him Reincarnating, he finally gains the ultimate Dojutsu.