Top Tier Providence, Secretly Cultivate for a Thousand Years - Chapter 3: Seventh Level of the Qi Refinement Realm, Too Charming

[Mature Smut Contents!]When a deadly virus turns the world into a nightmare, high schooler Ryan gets bitten by an Infected—along with his crush. Facing certain doom, they decide to go out with a bang, losing their virginity in what they think are their final moments.But surprise—they don’t turn. In fact, they’re cured.Turns out, Ryan’s seed has a miraculous side effect: it heals infected women. And that’s not all—he soon discovers unique powers of his own. Now, in a world overrun by monsters, Ryan has a new mission: survive, thrive, and build a sanctuary of powerful (and stunning) women who owe their lives to his very special ability.

A surgeon accidentally got the blessings of a system, shocked the medical industry, and rejuvenated countless people.

- Description from Novelupdates

After 2000 years has passed, the ruthless demon lord has just been reincarnated! But his aptitude at an academy for nurturing candidates for demon lords is, “Inept”!?

The world had changed when the System arrived, alongside the Cataclysm that filled the world with monsters. The technology was gone, replaced by classes and skills that allowed the people to fight back. When Devon ended up as a Blacksmith, a class that didn’t grant Intelligence, he had to face the reality, that his old career that he loved - mathematical sociologist - was over. Instead, he had ended up as yet another discarded member of the production class, overshadowed by the existence of the System Shops to the point of total marginalization. But, what if all he needed was to reapply his scientific thinking to the System...