Surprisingly, Japanese also display the highest frequency of haplogroup O3a5, which is a Han Chinese and Sino-Tibetan specific O3 branch.
Japanese Haplogroup O3a5 (O3e) 10/47= 23% This frequency is about 5% higher than the frequency of O3a5 among Manchus, Koreans and other Northeast Asians.
Another study published in 2005 on 81 sets of Y chromosomes of six populations across Japan showed: – The Japanese have at least two very deep pre-Yayoi ancestral Y chromosome lineages (D-P37.1 and C-M8) that descend from Paleolithic founders who had diverged from the mainland and that were then isolated from those populations on the mainland for a very long time.
Scientists thought these D lineages to mean the Jomon populations in Japan once upon a time the same ancestors as Tibetans from central Asia who are found with the highest frequency of continental D lineages is found in central Asia.
The DNA sequencing picture that emerges today shows the central Honshu people of Japan to be genetically just a little closer to Sino-Tibetan and Han Chinese (from the Jiangsu region who were possibly rice-farming immigrants during the Yayoi era) evidenced by the specific genetic Y markers found in Japanese today (ie O3a5, O3a and O1), in their mix than to modern-day Koreans whose ancestors contributed significantly to the Japanese gene pool probably during Koguryo and Paekche migrations into Japan of the Kofun era to Asuka eras.