Photograph (left) shows an instrument with a body slightly flattened horizontally, while that in the center shows an instrument slightly flattened vertically. On the right is an instrument with a rather slender body. These kind of differences are more important than might be thought.
Generally the instrument flattened horizontally is termed hirami. It is easy to hold and easy to play. The shakuhachi that is flattened vertically is termed kodaka, and is a little more difficult to hold and play. But because the holes are deep, the tone becomes more colorful. The slender instrument changes tone rapidly but lacks strength. The are the special characteristics of the various instruments. --Kitahara
