Mr Owens,

The illustration of 'shinansha' in the "Daijiten" shows a man standing in a cart holding his arm out. Clearly the term has changed its meaning from simply pointing in a certain direction. As for 'yaku', there is a constant slide in meaning from the office to the person who holds the office, as in the phrase 'torishimari yaku', for example, which means director (of a company).

If it indicates a teaching rank, as it appears to do in some martial arts schools, it is presumably given by the organization or school. In the web site indicated, the word seems to be merely a title, which can be empty, or not, as the case may be.

Best regards,