House of The Dragon-A God Amongst Men - Chapter 360: Five Days: Fifth Day

As the owner of an ordinary bookstore, Ling PingAn’s biggest wish was to muddle through life and do absolutely nothing.

A man was transported to Ancient China and eventually became a servant of a declining household without a male heir. He utilized his wits and modern knowledge to help the household and eventually become trapped in the sea of political turmoils of the period.

- Description from Novelupdates

The world experienced a cataclysmic change, and countless spatial gateways appeared out of thin air.

After 20 years of dedicating his life to opera ever since he had quit the performing arts high school, he had failed at an interview. Losing his motivations, Jo Yunjae depended on alcohol to live out his days until one day, he had been sent back 20 years in time, to the day before his high school admission.