His wife.

The song is addressed by a girl to a suspicious lover; Genji reverses the sense.

‘Though I know not the place, yet when they told me this was the moor of Musashi, the thought flashed through my mind: “What else indeed could it be, since all its grass is purple-dyed?”’

Fujitsubo. The fuji flower is also purple (murasaki) in colour.

The child Murasaki, who was Fujitsubo’s niece. Musashi was famous for the purple dye extracted from the roots of a grass that grew there.