The following is what I have recently found about my ancestral journey by the results of a DNA test administered by the Genographic Project https://www.nationalgeographic.com/genographic/, a joint project by the National Geographic Society and IBM, whose goal is to analyze human DNA samples and understand the routes which human populations took.
After submitting my DNA — obtained simply by swabbing the inside of my mouth —along with $100 and postage, I received some 8 weeks later information about my paternal ancestors.
My earliest ancestor (some 50,000 years ago) is from somewhere in the Rift Valley region of Africa, i.e., the present-day “Ethiopia, Kenya or Tanzania”. About 45,000 year ago, another male ancestor came somewhere in the Arabian peninsula or present-day Iran.
Five thousand years later, another ancestor was born in Central Asia, and then another one came to Southern China some 35,000 years ago where my ancestral journey ends. I am told by the report of this project that my DNA (M175) indicates that I am related to more than half of all present-day Chinese males.
My speculation is that a few thousand years later, one of my ancestors decided to get out China and sailed to the Philippines for warm weather as the ice-age was in full swing then. From the Philippines, it was seemingly easy to come up to Japan, via Okinawa, on the Black current.