Hoping someone here can fix this...
The artist name "Mukuzou" is wrong. If you look at the copyright notice at the bottom of his web page (cragra.h.fc2.com) you'll see it's "Ryoh-Zoh".
Updated
Posted under General
First of all, you can link to tags by enclosing them in [ [ and ] ] (without spaces). Like this: mukuzou. Second, the artist tags we use very often don't reflect what the artist themselves use in their signatures, for a variety of reasons. These reasons would be:
1. Japs suck at romanisation. Other people who romanise Japanese names suck at it too. OTOH, we have consistent romanisation rules we apply wherever possible, meaning the above would be "ryou-zou" at best.
2. Artists often change their names and/or go by several different nicks. Very often they're commonly known as X, but that's actually just the site name and the artist really goes by Y. Sometimes it's not the site but the circle name. In this case we will use Y, not X, to tag.
3. If the real name of the artist is known, we will use that instead of whatever nick they may use.
4. Finally, there might be conflicts. If we run into two or more artists using, say, "ayumi" (made up example) or something similarly prone to clashes, we have to disambiguate them somehow. That often means using secondary nicks or site names as qualifiers.
For all of the above reasons, just because the artist uses something to sign their works doesn't mean it's correct for danbooru's purposes. As long as proper aliases are in place (aside from #4 above, where we obviously can't set up any), it's okay.