When initially encountering japanese jazz years ago, I thought most of it sounded derivative and at times bordered on mimicry of contemporaneous American jazz. Having listened to a lot more and being a bit more familiar with some of the bigger names (although far from being knowledgeable), I find that the truth is a bit more nuanced of course. Nevertheless there is more than a grain of truth to my earlier view. For instance, there is much to appreciate and enjoy in Jazzman's 3 volume comps but only a few of the tracks especially stand out to me, and make me want to seek out more of the artists' work.
The Guardian article is not particularly insightful. Most of it seems to be based on the writeup in the Jazzman reissues and the artists they covered. For me (so far, in my ongoing japanese journey), the big names are Sadao Watanabe, Masabumi Kikuchi and Terumasa Hino. They all made interesting albums from the late 60s to the early 80s, sometimes together. The Watanabe of that period is nothing like the smooth fusion jazz or neo bop music that he played in the 80s and later.
Other artists worth pursuing are Kohsuke Mine and Aki Takase. The failure in the article in mentioning Yosuke Yamashita is a notable mistake. Perhaps he played more free jazz and therefore is outside the purview of the article and comps.
The biggest problem you will have in exploring this stuff is obtaining the records. Japanese jazz like some other genres of jazz has become extremely collectible especially on records. Even in Japan, many of the records are expensive and hard to find. Over the last decade, there have been more reissues in Japan of this music but they are pricey and not easily available outside the country. For this reason, the Jazzman reissues and comps are a godsend. And if you are fine with CDs, you will have more choices and the cost of entry is far lower (but you'd have to order from Japan).
In terms of availability (rather than specific recommendations), you may be able to find some of Watanabe's early albums because he was a major Sony artist. Takase made a great album on Enja (track featured on J Jazz vol 3). Hino also recorded with Mal Waldron on Enja. Yamashita collaborated with Joe Lovano on a few albums in the 90s, so these CDs may still be found second hand.
P/S: Three Blind Mice is highly regarded among audiophiles. Personally I find most of it pretty insipid and unadventurous music-wise, with some exceptions.