Unfortunately, although I have a fairly good knowledge of medieval European history, my knowledge of Asian history is severely limited. I did take a World Cultures class in college, but we spent most of our time studying Hinduism and I remember the Chinese history as being notable largely for how confusing it was.
There were plenty of crazy Roman emperors (my personal favorite being the crossdressing Heliogabalus, who once married a statue). Caligula, Nero, Domitian, Commodus, all have notably insane acts ascribed to them. So I’m sure there had to be some completely batshit emperors in China, as well. Any examples?