One of the most distinctive sounds of Gagaku is the strong nasal tone of the hichiriki. This is the most widely used of all instruments in Gagaku and is used in all forms of music aside from poetry recitation. It is said that the sound of the hichiriki expresses the voice of people living close to the earth. Often the main melody of a Gagaku piece is carried by the hichiriki, but the range of the instrument is only about one octave, so a very rich range of embellishment techniques developed. For example, there is the technique called "enbai." The double reed for the hichiriki is very large so that even with the same fingering, just by altering the pressure on the reed a range of three pitches or so can be reached and a kind of portamento can be created.

The body of the instrument is a length of bamboo 18 cm. long 1.5 cm. in diameter and it is relatively elliptical. There are seven finger holes on the front of the instrument and two on the back. The ends of the instrument and sections between the finger holes are wrapped with thin strips of birch or cherry bark. The reed, which is called "shita" or "tongue," is 5.5 cm. long. It is made from ashi reeds with the skin peeled and the two sides brought together. The end that is pushed into the instrument is wrapped with Japanese paper and the two parts of the reed are held together with a length of rattan cane. The reed needs to be moistened when the instrument is played and soaking the reed in hot green tea is considered best.