I lived in Shanghai for 3 years with monthly trips to HK. Cannot really look seriously at Chinese food in the City anymore. Far better elsewhere.
I currently live in Tokyo. Have done so for 34 years. Japanese food, is best eaten in Japan. Period. As for vegan being called Shizen which means "natural" this is not correct. We call it Vegan using the katakana alphabet in most situations (
ビーガン). Of course much easier to understand n Japan is the style called Shojin Ryori served at Buddhist temples and at restaurants following those principles (i.e. not killing anything) and which is as vegan as it gets. Some of these restaurants even have Michelin star ratings. And that is just in Tokyo. So much beyond Tokyo as well.
While some folks, even some Chinese immigrants and some who are of Chinese descent, claim to prefer the food in the City, for truly next level Chinese food and even remotely authentic Japanese, elsewhere (i.e the point of origin) is really the best choice.
If I was going to Tokyo as a tourist, I doubt I would check out any vegan offerings. And the whole point of Mr. Jiu's is
not that it is authentic Cantonese...it's not. As I said, I haven't been, but I am intrigued by the concept, which I think is fairly unusual, and I would warrant is not that easy to find even in HK (although e.g. Tin Lung Heen at the RC might be conceptually similar, and having eaten there, I really enjoyed it). I have only visited Japan as a tourist, and for sure don't understand the culture like you do. But I think you misunderstood: Shizen
is the name of a vegan Japanese restaurant in the City. I, for one, had not seen vegan Japanese restaurants in US cities before coming to the Bay Area. I'm sure you will be able to find dozens of examples, but I was sharing my experiences and recommendations.
tb