Compare to a Confucius-style lacquered qin also bearing the signature of Li Cangwu sold at Christie's Paris, 11 June 2014, lot 40.
The inscription on the back of the qin is followed by a seal, Longsheng, which may be the seal of Tu Long (1543-1605), a late-Ming writer and dramatist. Comparison of the calligraphy style of the inscription on this qin and fan leaves by Tu Long reveals close similarity. Longsheng is also the pseudonym of scholar-official Shen Yinfang (active circa late Ming), who passed the jinshi level of the Civil Services Examination in 1628, thought it seems more likely that the signature belongs to Tu Long given his expertise in music and the similar calligraphy style.
The current qin was in the collection of Nakamura Kouma (dates unknown) prior to 1928 and was recently acquired by the current owner Shugetsu-sai in Kyoto. Shugetsu-sai studied after renowned qin masters Sakata Shinichi in Tokyo and Wang Di in Beijing, and held a public performance using the current qin at the exhibition Shuzan Hakugen-ten at the Matsumoto City Museum of Art in 2014.