First of all, this artist is not unknown, merely dead. All credit for some (I'll explain that later), but not all, of these works goes to the Anichara CG Gallery, a tribute to which exists here:
http://www.geocities.com/anichara_cg/, and has all the pictures ever done by the artist.. Anichara, as I've taken to calling the artist, had a running site on the Biglobe network roughly three to four, possibly five, years ago. Now, to what I mentioned earlier....
In the second post, the middle three are not of Anichara. The style, for one, is slightly different, and for two, they were never on Anichara's website, which held all works done by him/her. You can usually tell a true Anichara from a copy of the style (Of which there exist MANY examples) by the coloring job. True Anichara images have a 'glossy,' almost plastic and shiny appearance, while those three do not. The same reasoning applies to the last image in post six.
As to the last two posts.....I believe with certainty that they are simply copying his style, and not actual Anichara pieces. For one, they were never on his website, and as I said, it held all pictures he ever did. Secondly, they are different in color and style. Thirdly, and most importantly, I can place nearly all of them as having appeared AFTER the Anichara CG Gallery died, thus placing them outside the realm of "Early Works."
I hope that gives you some info. At least one artist has been identified.
And Owen beat me to the ID and link....I'll just leave this unedited, so pardon the repeat of information.