Definitely a classic among old Japanese Metal labels. Their signings tended to be on the more melodic side of things, but thankfully not in a yuchy aor-way. As with many other of my discog pages I've only bothered with the first edition of the label, in this case 1985-1991. Albums start right below, flexis begin here and demos start here.

Rather late in my research I came across this Japanese page which also lists the Mandrake Root discography. It looks like it could be complete, and also includes some later sub/sister labels. No info on the flexi-releases though, but it did help me with filling in some missing demos and the odd CD.