Maou na Ore to Fushihime no Yubiwa - Volume 1 Chapter 1 — The beginning of the nightmare

While reading a book, a sparkle of light disappeared. And, as it did, a message appeared.

Hyde arrives in a doomed world with nothing but his body and fragmented knowledge of the future from a game he once played. He has no grand ambition—why try to save a world already destined to fall? Survival is enough.That is, until he discovers his sister is also transported into that world.However, only he hears the Melody of Nightingale and receives the power to survive.[You have established a connection with The Forgotten Hollow.]Awakening as a Resonant—an elite group with supernatural abilities—he is thrust into a conflict between two worlds. Armed with the authority of space and time, he vows to protect his powerless sister at all cost, even if he has to fight against the Mirage creatures, other Resonants, or even Gods themselves.

In order to live he must get close to girls, what kind of rule is this? Tang Zheng possess the Nine Yang Saint Body, a rare body constitution that is hard to come across within a millennium, yet he must absorb pure Yin energy to stay alive. In order to live, he will fight! Absolute campus belles, goddess teachers, charming housewives, haughty lolis… all kinds of woman walk into his life causing him to be surrounded by beauties!

- Description from Novelupdates

In the legends that were told, ten thousand years ago the twelve demon kings wreaked havoc upon the world, almost completely destroying it. Ten thousand years later, the late arriving Bella discovered that she had been screwed over by her reincarnation, the ranks of the Saviors are already filled and she has to change teams in order to pass the days. Having her gender changed into a beautiful girl… she endured that, not being able to join the righteous side and obtain cheat abilities… she endured, but what she could not endure, was that the world that she had transmigrated to was toxic beyond belief. No one here does their rightful jobs properly, be they heroes, demon kings, or creator gods… in fact, Bella felt as if they all had also started with the wrong faction!