Former General Is Undead Knight - Volume 2, Chapter 12: Feudal Lord, Earl Mondo?

By coincidence, Li Yunmu found a super machine from humanity’s age of darkness. From that point onwards, his ordinary life would never be the same! Aptitude? Innate talent? What are these? Could they be eaten?

I have neither aptitude nor innate skill, but my shadow can level up using hacks. Experience, Ability points, battle prowess… all of them could be hacked. Even while he is asleep or tired, he could still increase his skills.

- Description from Novelupdates

Two years ago, the mere fifteen-year-old scion of the Lin family, in front of the colossal behemoth that is the Murong clan, made a vow!Two years later, no one knows what he has gone through, but from the moment of his return, he radiates a brilliance that seems to compete with heaven and earth!(Note: The protagonist of this book is very aloof, cold, and passionate. Those who like to read about a military king's ambiguous romances and flirts, please bypass this one.)

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.