I Will Create a Good Ending for the Yandere Villainess - Chapter 21: Playfulness?

He wants indoor plumbing. They think he’s conquering the world.Arthur was a genius engineer on Earth, capable of optimizing global logistics and automating entire factories. But he lacked one thing: common sense. Now, reincarnated as Arthur von Pendelton, the six-year-old son of a powerful Duke in a medieval fantasy world, he faces his greatest challenge yet: Drafts.Armed with the T.E.C.H. Interface (Trans-Epochal Construction Heuristic), Arthur can analyze magic like code and build modern technology from scratch. His goals are simple: Double-glazed windows, hot showers, and a toaster that doesn't burn the bread.But there is a problem. The people of this world don't understand engineering.He builds a high-pressure boiler for a bath; his father thinks it’s a “Dragon-Breath Siege Weapon.”He creates a hydroponic garden; the local church declares him the God of Harvest.He ignores a Princess's flirting to analyze the thread count of her dress; she thinks he is playing “hard to get.”Follow Arthur as he accidentally industrializes a kingdom, terrifies his enemies with home appliances, and remains completely oblivious to the fact that he is becoming the most powerful man in history.All he wanted was a warm bath.

A boy born with the potential, so great that it threatend the world's powerhouses itself._____Born amidst chaos and tragedy, Azhrael, the son of the legendary Frost King and Celestial Witch, carries a burden no child should bear. Half of his soul was dormant into another world, while the other half was left sealed, hidden from the prying eyes of those who sought to destroy him.He was a child of immense potential—his very existence threatened gods and shook the balance of power in the world.However in the main story, Azhrael was only an “extra.” A mysterious beautiful boy with snow-white hair and dull grey eyes who exists in the shadow of others, bullied and beaten, unaware of the legacy he carries.That Is Until.

The figure of the Armada seems to be still riding the wind and waves in the Atlantic Ocean, and the gold of South America still seems to flow in continuously. As Alfonso from the Bourbon family returns to the Royal Palace of Madrid where he was born, the story begins here…

- Description from novelbuddy

The first time they met they had battled fiercely, just for a mere bunch of herbs. She needed it to save people, and he wanted to use it to save his own life.

“Let go of it, or you will die.” The man’s violet eyes were cold and sinister as he said in a low voice.

She held on tightly to the base of the herb and pulled its roots right out of the ground, before she turned her eyes back with a crafty smile. “It’s mine now. Snatch it from me if you can.”

When they met several years later they were no longer on opposing sides in hostility. In order to repay the debt for having stolen the herb back then, she went on to miraculously cure his body’s condition, relieving him of the inhumane torment that wrecked at his body day and night. He was amazed by the godly skills in Medicine she possessed and his heart went on to fall irrecoverably head over heels in love.

- Description from novelupdates