Stranger's Handbook - Chapter 16: Training with the Soldiers

The Imperial Court of Tang Empire became dim and corrupt. The Emperor believed eunuchs. The officials vied with each other for authority. The Tang Empire was about to collapse. The flouring Confucianism, Buddhism and Taoism eyed it covetously. The three sects wanted to contend for the domination of the whole world. Which one would win in the end? Or would they coexist peacefully at last? Armies of different nations invaded the frontier on all sides. People and the whole world were in extreme misery. Who could save them?

A young man of the Imperial Clan was reborn in Chang’an. In the Last Life, he was framed and was driven out of his place. He was the king of the subjugated country. When he wandered on the streets, he wanted to be an ordinary people and live an ordinary life in Chang’an but failed.

In this life, he determined to fight against the heaven and change his own fate. He would not give those people an opportunity who framed him in his Last Life. He would hold his title and his place. In order to maintain order and peace of the world, he was going to wipe out all villains of the whole world with the Imperial Sword, adhere to the emperor’s principle, and enact the new national law. He would rule over the empire to prove himself.

- Description from Novelupdates

Spend life energy to infuse martial arts, and you can perform unlimited deductions.

Shen Yi’s mortal body only has a lifespan of less than a hundred years. Fortunately, he can gain his remaining lifespan by killing demons.

In the troubled times where evil spirits are everywhere, the long sword is revealed, causing the liver and gallbladder of these creatures who have lived for thousands of years to burst!

From [Eagle Claw Technique] to [Eight Desolations Splitting Heavenly Hands], from [Demon Subduing Fist] to [Golden Body Prison Suppressing Dharma Appearance]!

Shen Yi occasionally ponders, how come this lifespan is getting longer with more use?

He put the sword into its sheath, raised his eyes to the sky, and heard that there was a Jade Palace above the clouds. It was filled with thousands of saints, each of whom had experienced endless years.

This time I came to heaven just to borrow a million years from the immortals to prove my path to immortality.

- Description from novelbuddy

____this story sets in Japan that developed a little different history from yours.

This is how a Japanese Princess relieves her stress of the day by using the latest VRMMORPG, and while playing the villain there, the first town turns into whirlpool of chaos, smashed the underground organization in one hand and went for a coup. It’s literally a playtime diary of a girl who is called as “Genocider-san”, “Roaming Last Boss”, “A different person plays the game”, “Raid Boss”, “Ruthless”, “Calamity”, and such by the players.