Harem Dynast - Part 1: Chapter 3 - The Conqueror’s Queen

Well-known Composer Fang Zhao was in the glorious stage of his career, when the Apocalypse arrived; After finally experiencing the bitter difficulties of a thousand dangers, when the Apocalypse was simmering down to an end, he collapsed; When he opened his eyes, he was reborn in a New World, 500 years after the end of the apocalypse, in the body of a student who had been dumped barely after graduation, who had been cheated of his hardwork barely after he started working…

A mysterious natural phenomenon caused the Earth to be plunged into darkness. The world turned into an endless bloody chaos and mankind is on the brink of extinction…

Chu Yun Sheng, an ordinary white-collar worker, discovered his family heirloom book shining a bizarre light by accident. Out of curiosity, he tried to study the heirloom book.

After a long research, he still only understood a few symbols written in the ancient book. However, he was shocked when he figured out what messages the ancient book tried to tell him: the sun will disappear, and humanity is doomed…

He tried to spread the message, but no one believed him; his family and friends even tried to take him to see the psychiatrist. Eventually, he gave up telling anyone, but prepared for the apocalypse in secret.

Until one day– the sun really disappeared…

- Description from Novelupdates

…but it seems pretty doable.