I was looking at Kiwaya's website, and saw some text about "the ukulele's bitter history in Japan". I had no idea what that meant (still don't); maybe it was just a translation error. Maybe it relates to Western music being banned in Japan during WWII, when there were many uke bands there, possibly playing Western music?
Throughout the 1800s Hawaii was a busy supply point first for the very profitable trade of Pacific Northwest otter pelts to China and later for trade between San Francisco and China. Shipping lines offered frequent service for goods and travelers.
Excerpt from Wikipedia:
"After Europeans and mainland Americans first arrived during the
Kingdom of Hawaii period, the overall population of Hawaii—which until that time composed solely of Indigenous Hawaiians—fell dramatically. Many people of the Indigenous Hawaiian population died to foreign diseases, declining from 300,000 in the 1770s, to 60,000 in the 1850s, to 24,000 in 1920. Other estimates for the pre-contact population range from 150,000 to 1.5 million.
[15] In 1923, 42% of the population was of Japanese descent, 9% was of Chinese descent, and 16% was native descent.
[147] The population of Hawaii began to finally increase after an influx of primarily Asian settlers that arrived as migrant laborers at the end of the 19th century.
[148]"
en.wikipedia.org
en.wikipedia.org
In the 1800s American industrialists clear cut Hawaiian forests to establish gigantic industrial scale plantations for sugar cane, canned pineapples, and cattle to be exported to the USA, Pacific Rim countries and Europe.
Companies needed to bring in huge numbers of workers because the native Hawaiian population had fallen by 90% and the survivors didn't really want to switch from their sylvan lifestyle to toil on plantations. Plantation owners were happy to encourage communities of contract workers and settlers and small businesses because it meant they did not need to provide supplies, transportation, housing, schools and infrastructure.
(Amongst them were Azores families displaced by agricultural disasters at home, and who introduced the machete aka ukulele to Hawaii.)
By the 1920s ukulele boom (as described in the Ukulele Magazine article) the Japanese community reached 200,000 and maintained robust linkages with relatives in Japan. The most successful immigrants could afford to travel, and to send children to Japan for schooling. The Japanese community enjoyed playing and making ukuleles as much as other Hawaiians, and naturally took ukuleles to Japan.
During WW2 the Japanese Americans in Hawaii were not sent to internment camps like those on the US West Coast. Which meant that at the end of the war they still owned their homes, possessions, and businesses and were prosperous and able to be part of the 1950s ukulele revival in Japan. Ukulele performers and teachers traveled frequently between Hawaii and Japan.