These artists haven’t been heard from in years…
Huge fan of Detective Conan on Twitter who regularly shared news and memorabilia related to the boy detective, and may have published doujinshi as well. In late 2017, they changed their Twitter handle from @nemui_sec to @4423_abz, then disappeared from Twitter in late 2018.
The Conan dress-up game they created (http://nemunemui.web.fc2.com/c_ks/) is still working, as of 2020.06.04.
Circle of artists who made fan art of the classic shoujo manga, Kaze to Ki no Uta.
They stopped updating their website (http://www12.plala.or.jp/tukiiromangekyou/) in 2010, though the last dated illustration I have from them comes from 2008. Their site now returns a generic “Page not found” by Japanese ISP Plala.
Yuzuki Ichi was an artist who made primarily BL and shotacon works. They were active in the early 2000s, providing the character designs for the adventure games Kannagi no Tori and Laughter Land, and self-publishing contemporary romance, fantasy, and historical fiction manga.
Around 2010, they announced they were taking an extended break. Their website, Wildcard Project (http://www.ncn-t.net/yuzuki/), now returns only a generic welcome message by the defunct Japanese website hoster WebSpace.