Wait, What You Mean I Got Reincarnated As A Heroine In Another World? - Chapter 9 - Helena

In the foreign world, the martial artists dominate the world and the sword of the emperor controls the fate of hundreds of millions of lives! Long Yu, the number one killer on Earth, after dying, takes rebirth in this new world in an aristocratic family of martial artists but faces rejection because he is unable to practice martial arts.

- Description from Novelupdates

Lin Wanwan slips a jade bracelet onto her wrist—and steps between two worlds.Side A: neon lights, 5G, instant ramen, MRI machines—an age of abundance where food is fast and friendships sometimes slow.Side B: Tang-dynasty sunshine, cracked earth, locust clouds, emperors who ask villagers to skip meals so soldiers can march. A “golden age” that growls with hunger.Lin has no grand plan—only a wish:let the little bean who waits for her at the gate eat his fill,let the gray-haired elders who calls her “treasure” sleep without fear of famine.Lin Wanwan wants to bring small changes to the world she loves, so the family she cherishes can live a little better, then a little better still—because“I has finally found the place that calls my home.”

The leader of the thousand demons, the Demon God Chun YeoWoon. Due to an unfortunate accident, he had been sent to the distant future.

I freed the Slaves, but for some reason, they keep chasing after me.