The North American Indians of Japan - if a genetic comparison is done, it is highly likely the Ainu will turn out to be similar to the Inuit and the Native American and Native Canadian indigenous people.
Very likely that was the direction of the migration, just a small detour to the south from the Bering land bridge.
“The North American Indians of Japan - if a genetic comparison is done, it is highly likely the Ainu will turn out to be similar to the Inuit and the Native American and Native Canadian indigenous people.”
From what I’ve read in the past, the Ainu are Caucasian.
The Ainu relocated to Hokkaido and other Northern islands shortly after the Japanese emperor managed in the 1300s to finally conquer the last Emeshi, the modern name for the original inhabitants called the Jomon.
The Emeshi had been gradually converted into a warrior class called the Samurai. They were relocated from the Northern islands to Fukuoka as a sort of Samurai Central where they could be dispatched to the wealthiest cities and prefectures of Japan to enforce the Emperor's rules.
Shortly after the Emeshi were evacuated from the Northern Islands the Ainu took their opportunity to move inn.
As far as being related to the American Indians is concerned, the Yakut people, who conquered Korea and japan in the 6th century, are close relatives.
The Emperor and his relatives (the hereditary daimyo, the imperial families, etc.) (a whale of a lot of people in Japan), are descendants of the Yakut. So it'd be the Emperor who is the relative of the Indians, the Ainu who are not!