Raidorl Seiken Senki - Chapter 1: Pitch-Black Holy Sword

Lucas Yohan, originally born in a world filled with magic and mana, gets transmigrated for the second time into an advanced interstellar world that blends strange magic and technology in ways he never thought could be possible. Upon awakening, he discovers that his transmigrations were no coincidences and is now in possession of the Crafts-God System, a system dedicated to creating a new successor to the deceased Crafts-God, who is an existence with the ability to create anything and everything. Lucas decides to fulfill the goal of the system and become the new Crafts-God, but he’s faced with an incredulous challenge; he can’t learn magic.

Based on the popular Vocaloid series, by HoneyWorks, called “Kokuhoku Yokou Renshuu (Confession Rehearsal)“:

Natsuki, a third-year at Sakuragaoka High School, who holds unrequited feelings for her childhood friend, Yuu, who’s in the Film Club. However, instead of being honest about her feelings, she makes him be her confession “rehearsal” partner. Unable to say her true feelings, things start to get complicated when Miou and Akari, who are also in the Art Club, get involved! Will she ever be able to confess for real!?

She was a peerless genius in the way of medicine, holding the Medicine King Cauldron in her hand.

Once she transmigrated, she became a lowly little medicine slave in dispensary.

Physicians made her life difficult, princesses humiliated her, even her fiancé came knocking on her door to break off the engagement?

What was that?!

However, she had the cauldron in her hand; the top-notch medicinal herb was in her hands. She stole rare and precious herbs, punished the slanderous, plotted against the petty, treated the Emperor’s sickness, and saved the Crown Prince.

Then, the imperial edict turned the medicine slave to a concubine and received endless doting. It was unbreakable. Wait… didn’t Prince Jun, who wielded great power in the imperial court, say she was a a detestable individual?

As the saying goes, the concubine was good in the way of medicine.

However…

- Description from Novelupdates

Apocalypse befell, and roommates performed a skyward ritual.As the fog descended, the Book of Blood Spirit appeared in the hands of all survivors, and only those with a Contract monster could survive.Su Han directed his gaze to the neighbor who had already mutated and twisted, silently pulling out a gleaming fruit knife...Grotesque meat corpses, giant spiders with gaping mouths, eyeballs enveloping the city, one-eyed sharp-toothed hand monsters...Civilization fell, cities shattered, and all humans became meat for the monsters. There was only one way to survive:Use monsters to fight monsters.