Manga Bits
Created by Youko [Yoko] Matsushita, Yami No Matsuei made its 1995 debut in Hana to Yume [Hakusensha publishers] magazine. It's currently serialized there, with 11 manga volumes [tankoubon] under that label.
In 2004, VIZ picked up license to publish the US english release of Yami No Matsuei. They will release YnM under the title 'Descendants of Darkness' by September 2004.
Anime Bits
YnM is also a yummy 13-episode anime series based on four completed arcs of the manga. It originally aired in Japan about 2001. The anime ended on its own accord, since the manga is ongoing. In 2002, Central Park Media released the complete US DVD edition under the title 'Descendants of Darkness'. Currently available in four volumes ^.^