Kyoukai Senjou no Horizon - Volume 7C, Chapter 61: Silver Cutter

Tian Man Continent is a world of martial arts. A young boy named “Su Yi” led countless yao (monsters or demons) and overrode countless families who had thousands of years of history. He rose abruptly in the world as the brightest star in the sky. He married beauties and walked towards the peak of of the world, and finally ascended onto the thrones of the ancient gods!

- Description from novelupdates

After coming out of a tunnel… it was pitch dark.

What's the book about? It is about Demonic Cultivation!, If you cannot handle it, Please don't read it.Synopsis:When Song Wen killed the frail beggar who fought him over food and consumed his blood and soul, every cell in his body leaped with excitement. His spirit was exhilarated, and he realized then that his life would henceforth be filled with slaughter. For survival, for longevity, he would spare no effort, even if it meant creating mountains of corpses and seas of blood.

Seven billion humans living on the Earth time-traveled together after they had woken up one morning. They all heard a synthesized female voice.