A. The utaguchi (歌口) edge on the front and the chin-rest portion on the back.
B. Finger-holes 1 through 5 (the 5th thumb-hole is on the back).
C. The bottom root-end which voices the fundamental.
Note: Some shakuhachi have a joint between finger-holes 3 and 4.
Shakuhachi (尺八) are end-blown flutes played with embouchure which is a specific shaping of the lips and mouth in order to control air-flow and pressure. Unlike Native American flutes and recorders, shakuhachi do not have a fipple mouth-piece to direct the air-stream. While shakuhachi embouchure is far more difficult, the reward is that the player can have much more control over the sound. The shakuhachi has six tone-holes, five of which are finger-holes, and it can play a little over two octaves. The natural scale of the shakuhachi is the minor pentatonic; however, shakuhachi players can access many more notes by adjusting the pitch in various ways.
For example, by lowering the head the player can bring their lips closer to the edge which flattens the pitch. The finger-holes can also be covered to various degrees to flatten the pitch which is called finger-shading. These two techniques are often combined which is called meri (メり). Additionally, the head and the lips can be moved in a number of ways to create vibrato and other sound effects. In short, it is the ability to manipulate the sound of the shakuhachi which makes it such a unique and expressive instrument.