Zither Emperor - Volume 1 Chapter 6.1

This is the story of Long Yi, who was killed because he took revenge for the girl he loved. Before he dies, a strange lightning carries his soul into a different realm. How will he live, when the first thing he noticed upon arrival is that, the man whose body he possessed is raping the country’s princess?

- Description from Novelupdates

I’ve possessed the mid-boss who tortures the protagonist and receives true education.Am I crazy? How dare I do such a thing to the person who is supposed to be the protagonist?I even planned to treat all the protagonist’s friends hospitably…“Everyone, wait for me! I will definitely become stronger and come to save you!”Oh. Running away.

[Your shadow is alive.][Feed your shadow, devour souls, level up, gain skills, complete quests, and grow stronger.][Do you wish to view your current stats?]In the magical world of Aetherus, Damon Grey is the weakest student at Aether Academy, relentlessly bullied and ridiculed for his lack of power and defiant personality. Yet, he endures the torment, clinging to his scholarship—the only thing providing him with the funds to keep his sick sister alive.After a brutal attack leaves him near death, Damon encounters a dark viscous entity in the forest that fuses with his shadow, awakening the Living Shadow System. This strange power grants him unimaginable abilities but comes with a grim cost—a relentless hunger for souls and flesh to feed his shadow.Now, with his shadow alive and insatiable, Damon faces a terrible choice: feed it to grow stronger or starve it and die with it.In a world ruled by ruthless nobles, deadly monsters, and power-hungry demons, Damon must decide if his newfound power is a curse or the only way to survive. With the Living Shadow System, his fate is clear: devour or be devoured.

Chen Sha came to a world of immortal martial arts and was ordered to take charge of the world’s first sect.

Before his death, the previous chief told him:

“If you don’t become the best in the world for one day, you are not allowed to go down the mountain for one day.”

So he closed himself in painstakingly, crossed the heaven gate in his body, and faced off against the ancient and modern powerhouses…

…

Many years later, Chen Sha recalled the day he went down the mountain,

From the moment he descended the mountain, he was number one in the world.

In the next ten epochs, any gods and demons have returned, immortals and Buddhas have lived in the world, ancient powers and ancient gods have appeared one after another.

No matter how the times change, he has always been No. 1 in the world and has never changed.

- Description from novelbuddy