This URI (
http://www.kanzaki.com/ns/keyword/) is an experimental namespace to map a (natural language) keyword or a tag to one or more things (Published Subject Identifier), each of which is described by a page of Wikipedia or Hatena keyword, or the concept defined in National Diet Library Subject Heading (NDLSH) of Japan.
For example, you may find this useful when you extract keywords from an XHTML page, and want to give them URIs with a disambiguation mechanism.
You can try a keyword - concept mapping with the following form. An RDF graph that expresses the relation using Word-Thing Mapping Vocabulary will be returned. If your agent is capable of XSLT, resulting RDF/XML will be rendered as an XHTML page.