So this is a slightly weird request, I'm working on learning Japanese right now, and I know one of the best ways to learn a language is to watch shows in that language. Unfortunately I'm also completely on the Chinese (or Korean) drama thing at the moment and haven't found a good J-drama to help me learn, my to-watch list for Chinese dramas is almost triple the size of my Japanese list :')

I'm looking for popular historical (particularly palace-based) Chinese dramas that have been dubbed in Japanese, but also have English subs. I'm a big fan of Empresses in the Palace, Empress of China, Love and Destiny, and Legend of Mi Yue, so anything along those lines would be perfect ^^

There are some old Chinese dramas and movies that have been dubbed in Japanese and can be found on bilibili or youku, but they have only Chinese and/or Japanese subtitles...

some examples:

The majority of these videos are only extracts, not complete series, though... Maybe you can try some Japanese historical dramas, i personally watched only Tempest and some movies such as Rurouni Kenshin and Onmyoji , but maybe here you can find some good suggestions: https://mydramalist.com/article/ask-mdl-and-now-for-something-different-historical-september-011012714

Sorry, maybe my comment is not what you were really looking for, but lastly just want to add my two cents: unless you want to study older ways of speaking, actually I wouldn't recommend watching historical dramas for learning a language, you will probably hear old-fashioned language structures and a lot of vocabulary that is not needed in daily life ^^''