Ancient Strengthening Technique - Chapter 3 Body Transformation!.

A college student, accidentally reborn into the world of Naruto, becomes a member of Uchiha who is destined to be exterminated.

In this cruel ninja world, in the face of endless wars and exclusion from the village, what will Uchiha Qing do?

PS: Later in the book, the protagonist will develop a system of immortal cultivation. Cultivating Immortals in the Ninja World, have you seen it?

- Description from novelbuddy

Of the ancient gods only one remained in the world. This god lived alone for thousands of years and no longer had any desires. Legend had it that during the great war between the worlds he used his powers to turn the tide managing to seal the cataclysmic rift bringing order back into the three realms. Time flew by and hundreds of years passed in the blink of an eye.

In this time Shen Li was born into the demon world. Known as the Azure Sky King she was used to living a bright and dazzling life full of successes. Little did she know that her 1000th birthday would bring misfortune to her doorstep – a politically arranged marriage with her name on it. The Azure Sky King would henceforth marry the thirty-third grandson of the Heavenly Emperor, Fu Rongjun. This arranged marriage was meant to unite the Heavenly realm with the Demonic Realm, bringing the two together. Most would consider it good fortune to be related to the Emperor.

Unfortunately Fu Rongjun was infamous throughout the two realms for his Casanova personality. As the King who called the shots in the Demonic Realm, she had the ability to quell uprisings and end wars with a swing of her silver spear – there was absolutely no way she would marry such a flirtatious idiot. She had to escape from this marriage somehow even if it meant death!

In her escape Shen Li, never expected to meet a man that didn’t belong to any of the three realms. This oddball was truly strange!

- Description from Novelupdates

Lady Bertia, who’s become my fiancée, is a bit odd. On our first meeting, she proclaimed herself a villainess noble girl who’s been reincarnated and said that she’s working hard every day to become a splendid flower of evil that’s elegantly put in her place.

I don’t get it.

But she entertains me because I don’t understand.

That’s why I think I’ll observe her for a while.

This is a story of a crown prince who’s so talented and handsome that he’s grown bored of his easy-mode life. A story of this prince observing a self-proclaimed villainess noble girl (who seems perfect at first but is a bit off) who’s become his fiancée as she snatches flags and breaks them into pieces.

As soon as Qin Feng opened his eyes, he was horrified to find himself lying in a drafty thatched hut. The problem was that he was still in his villa! What was even more horrifying was that there was another man lying under the blanket next to his legs!

“You, you, who are you?”

The man quietly sat up, exposing his upper body. He looked at him fixedly for a moment, then took a broken bowl from the table by the bed. He said in a muffled voice, “Wife, drink this water.”

Qin Feng rolled his eyes and fainted. Without permission, it is forbidden to reproduce or adapt it. Violators must be investigated.