Comic System in Naruto's World - Chapter 90

When he returned to the World of Martial Arts, the game was filled with blood and battles! Chen Kaixin had chased after the footsteps of the one emperor, two empresses, three princes, seven dukes, and thirteen aces for three years, but during the eve of the Sword Among Us tournament in Mount Hua, he was ambushed by evil bastards, and was killed so much that his level dropped to that of a newbie. He completely lost the chance to join the ranks of the powerful players in the game! In great disappointment, Kaixin quit the game and got drunk so that he could forget his sadness, but during that stormy night, Chen Kaixin found that he had actually dreamed for a total of three years, because when he woke up again, he woke up to three years ago, when he was still a student.

- Description from Novelupdates

A veteran gamer finds himself in a world similar to the game he played.You say you need to learn skills by leveling up? Sorry, I already know all of them.You say you have to meditate to level up? Sorry, I only need to fight monsters for that.

This legend tells the tale of the protagonist, Kuroki summoned to protect the demon king from the hero.

Kuroki, unbeknownst to him, suddenly came to another world. He was summoned by the demon king, Modes. The territory which the demon king overrules was in the midst of being destroyed because of the hero. He had no choice but to bow before Kuroki.

“Please save us, Savior Dono!”

Kuroki nodded, deciding to save the demon king due to an unexpected turn of event.

I killed the player.

He was one hell of a f*cker.