She wouldn't let the fisherman look in her wooden box, so they came up with this while story about her being a foreign princess, married for convenience, and took an illicit lover, so they killed her lover and put his head in the box and set her to sea.
That is an insane amount of bananas details for "she has a box and won't let us see what's inside."
The woman had red hair and eyebrows, the hair elongated by artificial white extensions. The extensions could have been made of white fur or thin, white-powdered textile streaks. This hairstyle cannot be found in any literature. The skin of the lady was a very pale pink color.
Red hair and pale skin, sounds like she may have been Ainu.
I've never heard that the Ainu were associated with red hair or pink complexion in any way. My guess would be that the woman and the boat went adrift off the cliffs of Moher and unusually strong currents just took them to Japan.