The Tyrant's Wife - Chapter 21 - Long Hands

From brewing whiskey out of car tires to brewing immortal potions just because they are tasty.Regressed from a world where the only issue technology failed to solve was boredom, Theo, an adept nanomancer and master brewer, finds himself in the literal shoes of magic academy's trash teacher.Cultivation? Magic? Martial arts? Craftsmanship?No.Now is the time for this world's first Nanomancer to rise and establish alchemy as the fifth great subject for others to follow!

Others treated disease to save person, he treated disease to steal heart.

The Frost Goddess was deeply captivated by him. The gentle and kind beautiful teacher was completely enchanted by him. Even the cold and beautiful female assassin melted quietly because of him.

Competing in medical skills? He was the one who treated the Godly Doctor. Competing with backgrounds? Leaders rushed to him. What? You actually wanted to compete with him in a match for match? Looking at the gentle girl beside him, Tang Yu had a headache as he said, “Beautiful girl, how did you fall in love with me?”

- Description from Novelupdates

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.