First of all id like to say that this is one of the best-written Naruto fanfictions I've read. It doesn't suddenly turn into some harem ecchi novel and it focuses on the power methods (mostly) in the naruto world.
Why did it end up with a 3.6 rating? Let me explain and if the author is reading then I hope this review helps.
Writing quality (4*): The writing quality is ok with no bad spag (spelling, punctuation, and grammar) and you can see it get better as the story progresses. You can definitely see the author's improvements. I gave it 4* though since the writing quality isn't anything mind-blowing but still flows nicely and is very readable.
Story development (3*): Ok so the start of the story was very cliche and I feel sets a rather bland tone for the story. He is some rich unmotivated kid with no real friends in school, gets stage 3 cancer and runs out of the hospital, sees a cat and while crossing the road is involved in a car accident. He then gets adopted by a powerful old ninja who helps him to train to become stronger because he has been told to do so by a mysterious individual.
Now there isn't anything bad per se with this setup but isn't anything groundbreaking either. Not to mention making the audience feel not super engaged with the story. Later on, he is thrust into interacting with the Hokage and some other heavy hitters while still in the academy, and once he finally graduates he is so far ahead of the main cast it's pretty laughable. He also is a rather righteous person which was a bit of a letdown since I do enjoy a more neutral leaning Mc. The fact he is in the shinobi world makes that even more odd since the story is a lot darker than you realize at first. With genocides, war constantly occurring and the leaf village being just as bad even with the preaching of peace I would have expected him to at least be less naive.
Still, he does get fairly strong, and although I don't agree with some of his choices like with the Uchiha massacre and the way he was dragged into that plot his reactions and actions do fit into how he has been portrayed so far.
A few ideas that could help could be getting the 3 tails that is in the lake if he hasn't been grabbed by the Akatsuki already, the peacock method could be explored, giving him other summons to learn from, learn or explore how hydrificaton works and if he can use other elements, even turn into a mist (plus with poison, he could become a poison mist or even make poison mist clones).
So the story is a 3* in my opinion, definitely could be better and I can only hope he can he doesn't become some Saint or savior of everyone and everything in need.
Character design (3*): the characters do fit their canon designs and their interactions do flow nicely and fit. However, the reason it's a 3* is because of the two main Oc Kensei and Daichi.
Kensei is the old man who adopted Daichi and while he is ok doesn't really have too much depth to him and is there mainly to kind of help shield him from the big players a little and to give Daichi a mentor figure who trains him. He does what he is supposed to though so no real complaints.
Daichi is a pretty typical mc. Nothing really special which is why I wasn't too surprised or disappointed with his good leaning. Would have been way more interesting if he was just fully selfish and thought about himself. Still, I am happy with the no romance (which I hope stays that way) and the confirmation of no harem.
Update stability (5*): updates are very regular which is nice, especially for when you want to wait for a little and binge all the new chapters at once.
World background (3*): it's just the naruto world which isn't too exciting but the methods of training the elements are very interesting. Hope things can continue in that vein.