It's Nico Nico Douga/nicovideo.jp. There is a unique community and reward mechanism that values technical achievements far more than it does for presentation, and that I think is forcing creators to go way past in skills than what YouTube and many other social media demands. That culture comes as an extension to Japanese anonymous BBS(2ch/futaba), and I find content from those communities to bear abnormally better quality compared to those from the Internet outside.

I can walk into Walmart, FYE or Hot Topic and walk out with Hatsune Miku merchandise. You can't even say that for many popular anime franchises (only stuff like Naruto or Dragonball that's been popular for decades). I've even been to small fan run projection concerts.

Vocaloid music has a huge following in the US. It's just a subculture thing and not part of the mainstream sphere...which is a good thing.

China has Luo Tianyi, Miku and co have had concerts in the US, and Miku was slated to perform at Coachella: https://www.rollingstone.com/music/music-news/hatsune-miku-c...

(Admittedly, those are not unlikely all offshoots of the anime/manga/etc. fandom though.)