My Yandere Succubus Daughter is Mommy-Warrior's Natural Enemy - Volume 1 Chapter 37

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.

After finishing playing mahjong, Yu Zhou, a recently resigned writer, returned home and found a young lady from ancient times, Xiang Wan, who was a former prime minister’s daughter, sitting on her sofa. After some simple communication, Yu Zhou, with her adolescent mind, accepted this “roommate” who had traveled through time.

On the other hand, Yu Zhou’s novel was adapted into an audio drama, which was unexpectedly performed by the well-known voice actor Su Chang, causing Yu Zhou to be overjoyed yet also in tears, because Su Chang was her ex-girlfriend.

Through their new connections, the girls re-examine their own lives and achieve personal growth. This absurd yet realistic experience may also “pat awake” Yu Zhou’s stagnant love life.

- Description from Novelupdates

In 2100 at the turn of the century the first full dive VMMORPG game 'Omega' was released

[NO. 4212: ‘Humanity’ has failed the Demotion Match.] [NO. 4212: ‘Humanity’ has been deemed useless. Beginning deletion.] As Earth was being erased after their final game ended in failure, Martial Saint Sung JiHan managed to resist deletion and saw messages pop up in front of him. [To think someone would be able to resist being erased.] [Let’s give him an opportunity to re-challenge.] [Player ‘Sung JiHan’ is returning to the time of initial entry in The League.] When he woke back up, he had regressed back in time. Given a second chance, he swore to himself to stop the fall of Korea and humanity and take flawless vengeance against those that ruined things in his original timeline.

Follow the journey of Korea’s Martial Saint, Sung Jihan, as he struggles to prevent a future of destruction and ascends as the Martial God!