The contact search allows for a search to specify which attributes of a contact are used (http://oxpedia.org/wiki/index.php?title=HTTP_API#SearchContactsAlternative ). Three new fields are added to this, named yomiFirstName, yomiLastName and yomiCompany. The prefix yomi indicates that this field stores a kana-based rendition of the name that was searched.
This behavior is similar to Outlook. This is also the way our own GUI works with input from the search field.