This is a reference to one of the Kojiki myths: Izanagi, one of the primordial deities of Japan, is said to have used tibiki nö ipa ‘thousand-pulling rocks’ to seal up the entrance of the underworld to protect himself from the anger of his deceased spouse, Izanami.

Yakamochi’s imagery here echoes that used by Tanabe no Sakimaro in his nagauta on ‘Seeing a dead man‘.

The Old Japanese believed that the soul actually left the body during sleep and so seeing the object of one’s affections in a dream was a significant omen.

The concubine seems to have been the mother of Yakamochi’s daughter – hence his reference here.