The Yu (竽; pinyin: yú) was a free reedwind instrument used in ancient China. It was similar to the sheng, with multiple bamboo pipes fixed in a wind chest which may have been made of bamboo, wood, or gourd. Each pipe contained a free reed, which was also made of bamboo. Whereas the sheng was used to provide harmony (in fourths and fifths), the yu was played melodically. The instrument was used, often in large numbers, in the court orchestras of ancient China (and also imported to Korea and Japan) but is no longer used.
Although the yu is now obsolete, it is known to most Chinese speakers through the saying "Làn yú chōng shù" (滥竽充数), meaning "to fill a position without having the necessary qualifications." The saying is derived from the story of Nanguo, a man from southern China who joined the royal court orchestra of King Xuan of Qi (宣王, 319 BC–300 BC), the ruler of the State of Qi (Shandong province) as a yu player. Although the man did not actually know how to play this instrument, he knew that the orchestra had no fewer than 300 yu players, so he felt secure that he could simply pretend to play, and thus collect a musician's salary. Upon the king's death, Nanguo was eventually found out as an impostor when the king's son Min (泯王, 300 BC–283 BC), who had succeeded his father as king, asked the musicians to play individually rather than as a group. On the night before he was to play, Nanguo fled the palace, never to return.