Lin Fan, an ordinary (or a bit otaku/social animal/technical nerd/history enthusiast) modern young man, lives in a dynasty similar to the Tang and Song Dynasties in China but in an imaginary way, the "Dayin Dynasty". The national power is medium, there are strong enemies around, there are party disputes in the court, and the harem is... A bit complicated.
The young emperor "Emperor Yin Ai" or "Emperor Yin Huan" (the name can be customized) who has just passed away (or is in an inexplicable coma) may have a bad reputation (foolishness, frailty, and neglect of government affairs), leaving behind a mess. The fierce collision between modern thinking and ancient systems and culture, the protagonist's complaints, saucy operations, and the daily life of being forced to do business.
Pretty good book