autosomally, the Ainu come up as East Asian. However, their male Y chromosome tells a different story.

significant percentages of Y haplogroup C1a exist across southern Japan. These percentages would have been twice as large before the Chinese invasion which brought haplogroup O.

This haplogroup C1a was also the dominant haplogroup of pleistocene Europe, 30,000 years ago, and was still around 10,000 years ago before the Aryan invasion. Which means that there was ancient paleoEuropean migration into Japan sometime after 30,000 years ago.