Sogonghu Korea Harp (literally "small harp" )
According to the Suseo (History book of the Su Dynasty), it were used for Baekje music. It is the smallest gonghu with thirteen strings. The body of the sogonghu is bent vertically.
A bigger variant is the daegonghu, it has a similar shape as the sogonghu but with twenty-three strings (similar to the Japanese Kugo harp)