Sanjo is a traditional form of Japanese music that originated in the late Edo period. It is characterized by its use of the shamisen, a three-stringed instrument, and often features a solo performer. The music typically conveys a range of emotions, from joy to sorrow, and is often accompanied by singing or storytelling. The term "Sanjo" also refers to a specific style of performance that emphasizes improvisation and personal expression. It is commonly performed in theater settings, such as Kabuki or Noh, and has influenced various other forms of Japanese art and music, making it an important cultural heritage.