The Chinese sanxian came through Okinawa as the sanshin and then entered Japan, where it can also be called the sangen.
As the name suggests, it has three strings; in China and Okinawa, snakeskin is used, but in mainland Japan cat or dog skin is used.
It was only since the early modern period that it was used in Japan, but it has been widely loved for a wide range of purposes, from theater music such as kabuki and puppet theater, to accompaniment for chamber songs, as well as folk songs from various regions. Depending on the genre, various sizes form thin-necked to thick-necked are considered standard, and there are variations in the shape of the plectrum and bridge as well. When plucking the strings, the plectrum is struck against the skin of the drumhead, and the strings lightly touch the surface of the neck, creating a lingering sound called sawari.
There are also many different tuning methods, including the standard honchoshi (a combination of a perfect fourth and a perfect fifth from the bottom), ni-agari in which the second string is raised by one tone, and san-sagari in which the third string is lowered by one tone. The reference tone can be freely set to suit the singer or other instruments, but is usually between B and D, and when written in staff notation, the fundamental tone is often written as B regardless of the actual pitch.