About Japanese Wikia community, I think that Japanese Wikia communities are quiet market, small groups, low populated and developing communities by comparison with several English Wikia communities now. I think that there are some reasons. @Wiki, wikiwiki.jp and PukiWiki software are in widespread use in Japanese wiki editor (@Wiki and wikiwiki.jp are based on Pukiwiki software). But these PukiWiki does not implement Category, Template and Namespace functions. Therefore, MediaWiki has a lead over PukiWiki on a technological edge.
Some of Japanese people go for anonymous societies. The "Contributions" (edit history) of PukiWiki, @wiki and wikiwiki.jp are anonymous by default. The edit history of PukiWiki and @wiki can be hidden. On another front, in Japanese Wikipedia, because the "Contribution" of Wikipedia are visible, we still can see some of Japanese Wikipedians often are get in each other's way in Japanese Wikipedia. Therefore some of Japanese like an anonymity. PukiWiki, @Wiki and wikiwiki.jp have typical anonymous edit history and have no edit summary. Their edit efficiencies are down little by little, because those wiki systems have no "Template:" (For more information, see http://www.creationkit.com/Category:Templates ).
Searching for "wiki" or "ウィキ" with Keyword Planner ( keyword tool), the results of the search are made mostly of subculture-related (such video game, manga and anime) keywords in Japan region and Japanese language. Searching for "MediaWiki" with it, the results of the search are made mostly of how to install/use MediaWiki and technical things in Japan region and Japanese language.
I am going for the Internet-Business schools (not educational corporation) now. From what I heard there, many people do not know what is wiki. The trend especially make an appearance in the middle-aged and older Japanese people. Some of them assume "Wiki" same as Wikipedia. Some of them assume there is no wiki other than Wikipedia. Some of them do not know wiki can be edited by anybody and everybody in essence. In addition, most of Japanese baby boomer (Dankai-no-sedai (団塊の世代), about 60 years old) do not gain familiarity with the Internet. In fact, most of them do not know even how to use a personal computer.
I think that need to educate people know nothing of wiki to expand the range of the Japanese wikia community. To that end, I think that someone need to issue a book to educate them. In Japan, there are few books for wiki since 2009. The books of WikiLeaks were highly visible in 2012. Thus, I think that wiki is largely-unknown in Japan.