yakumogoto 八雲琴 - Eight Cloud Zither

yakumogoto 八雲琴
(Eight Cloud Zither), the parent of the Nigenkin (Two Stringed Zither, a developed version of the yakumogoto)

Research: A two-string version called a yakumogoto was developed in 1820 by Nakayama Kotonushi. This instrument had a closed back resonant body and a bridge at either end of the strings. The yakumogoto has become strongly associated with the Shinto religion. An open-backed two string version, called the azuma-ryu nigenkin (Eastern school two string zither) was invented in the latter half of the 19th century by Tosha Rosen to perform popular pieces of the time.This version is often simply referred to as nigenkin, literally "two-string zither". SOURCE WIKIPEDIA

similar with the ichigenkin 一絃琴, literally "one-string zither", also sumagoto

made from Paulownia Wood ( I found this Instrument while searching for the ichigenkin, the one string zither )