The sho is a mouth organ. Like a bagpipe, it produces sound through a chamber that a player keeps filled with air by blowing into a mouthpiece.  It is a Japanese adaptation of the Chinese sheng, brought to Japan’s imperial court during the Nara period (710 - 794 AD).  Seventeen lacquered bamboo pipes extend from the wind box, to which a silver mouthpiece is also attached.  The maker of this instrument chose to decorate the wind box with a phoenix, likely because the pipes were thought to resemble the wings of the mythic bird.  Isabella was fond of the phoenix, an emblem of immortality, and one even decorates the crest of the museum designed by artist Sarah Wyman Whitman. 
Gardner displayed this mouth organ along with other musical souvenirs in the Franz Liszt Case in the Yellow Room.