Omniscient Reader’s Viewpoint (Web Novel KR) - Chapter 20

Zhou Heng drank too much wine, and woke up to find that he had time-traveled, and there was a beautiful woman lying beside him. Just when Zhou Heng, a bachelor of ten thousand years, wanted to take charge, he suddenly discovered that this woman who had a relationship with him was called Sadako, and she was the Sadako in Midnight Ring.

Sadako is just Sadako, pretty and human, but the memories that come out one after another make Zhou Heng discover that his name is Takeo Saeki, and he is the husband of Kayako in the Grudge of the Great Evil Spirit.

Later, at work, Zhou Heng discovered that his female colleague had a strange identity. The daughter of his client, Mimiko Mizunuma, had always been very interested in him when she came into contact with him.

- Description from novelbuddy

A striking man of mysterious origin and peerless talent, he looks back at the world, in all its entirety, with utter disdain. And yet, in the treacherous and unpredictable ultimate formation of the Boundless Secular World, he guards a breathtaking ancient qin with broken strings, waiting silently for the destined one to arrive!

A boy encounters him, and knows for the first time that the world beneath the Heavens is a fickle place. Not even demons, devils, ghosts and monsters can match the frivolity of human nature!

A slender physique, and jade-like beauty, but the sword that strikes between heaven and earth is not unlike a streaming rainbow!

The vastness of the starry sky, the seven emotions and six desires! Greed, anger and ignorance! The teachings of Buddha will grant you boundless strength!

A sea of blood will come, at the cost of all mortal beings full of honest hope!

The ghosts wail as the gods roar, but the sea of blood has no end!

Where, pray tell, is the path I should take?

Since there is no path, no matter how bitter and bloody the sea, even if my boat is made out of bones, I will soar to the heavens above!

- Description from Novelupdates

An Individual from Earth finds themselves in the Shinobi World, equipped with a Scientific System. From that moment, he delved into scientific research far ahead of its time.