Our chief instructors have delegated the care and feeding of the kyus, in terms of arranging and coordinating the testing and such. We're wondering what to call the guy. ...He's thinking something along the line of "supervisor" to follow the corporate model. I'm thinking that anything business like is an affront to the samurai traditions. ....
Call him "kyucho" which would be "head of the kyu-ranked students". As in kancho (head of the house, or dojo) or dojocho.
And this does also appear in business, as in bucho (section chief) or jicho ("next" chief), etc.
Further, don't underestimate the bureaucracy of the samurai. Once they moved past being just bushi, or "warriors" and became "samurai," they became exceedingly bureaucratic and, if anything, the Japanese business culture gets a lot of it's content from the samurai customs, more than vice versa.