The first inhabitants of Japan, the Jomon hunter-gatherers, had their culture significantly modified by that of the Yayoi farmers, who arrived at a later stage from mainland Asia. How this change took place is still debated, but it has been suggested that modern Japanese are the product of an admixture between these two populations. Here, we applied for the first time an admixture approach to study the Jomon-Yayoi transition, using Y-chromosomal data published earlier. Our results suggest that the Neolithic transition, in this part of the world, probably took place by a process of demic diffusion. We also show that for two populations that could not have contributed to this process, our approach is able to detect inconsistencies when they are used as parental populations. However, despite these promising results, we could not locate precisely the geographical origin of the Yayoi in mainland Asia, as different potential sources gave similarly good results. This suggests that more loci would be required for a better understanding of the peopling of Japan.