"...our data suggested that the Japanese population could be best modeled by admixtures of three ancestral components (hereafter K1 to K3). K1 to K3 were the highest in Okinawa, Northeast, and West, respectively (Fig. 1D and table S4). K1 (Okinawa) component maintains a relatively stable fraction of around 12% in Hondo subgroups, except for South (which is a region adjacent to Okinawa), with a higher proportion of 22%. K2 (Northeast) and K3 (West) components showed a cline from West to East."
Xiaoxi Liu et al., Decoding triancestral origins, archaic introgression, and natural selection in the Japanese population by whole-genome sequencing. Sci. Adv. 10, eadi8419 (2024). DOI: https://www.doi.org/10.1126/sciadv.adi8419
Cities and villages across Japan hold koinobori (carp-streamers) festivals in celebration of Children’s Day, May 5th. The koinobori are said to represent good health, happiness and success as a result of the courage and strength of the carp to swim upstream.