I'm writing a historical fiction novel set in the second World War. One of the characters is a Japanese person who has lived in China since childhood. However, as I attempt to flesh out this backstory, I'm finding it difficult to gather information on how/why a Japanese family & kids could have found themselves in China during the 1920s. I've read about the Japanese push to have their people immigrate to Manchukuo from 1931-45. This seemed like a perfect explanation, except the time frame is a little too late to work in my plot. What are some other reasons Japanese people would have come to China (a little earlier) like in the 1920s?
Actually, it was the formal occupation of Manchuria by Japan that began in 1931. But prior to this, the Japanese victory in the Russo-Japanese war led 1) to the Japanese occupation of Korea, 2) the withdrawal of Russia from Manchuria, and 3) the "infiltration" of Japanese into the resulting power vacuum in Manchuria.
In 1914, Japan joined the allies in World War I against Germany, and occupied the German parts of China such as Tsingtao and the surrounding area. Japan was forced to formally retrocede this to China after the war, but Japanese people had moved there in the meantime for business or professional reasons.
And even the United States, proponent of the Open Door Policy, conceded through the Lansing-Ishii Agreement of 1917 that Japan had special (commercial) interests in China.
Most Japanese migration to Manchuria occurred after its occupation and the establishment of Manchukuo in 1931, when it was state-sponsored, and mostly poor rural colonists. But there were smaller-scale migrations before that, numbering in the tens of thousands.
During the 1920s, Japan's major commercial venture in Manchuria would be the South Manchurian Railway. Mantetsu was by far the largest Japanese company, employing 35,000 Japanese nationals by 1910, and contributing over a quarter of tax revenues during the 1920s. Its most profitable business was freight transport of soybeans, grown in Manchuria for export, mostly by immigrant Han farmers. In 1931-1932 various estimates claim hundreds of thousands of Japanese nationals in Manchukuo.
I would expect the typical Japanese national living in Manchuria in the 1920s to be associated with Mantetsu, its subsidiaries (steel works, plants and mills, businesses dealing with colonial resource extraction), or related to them. He would be a professional, either rich enough to pay for his own immigration or useful enough for his company to pay for it. If he's well off, his whole family may have followed although this would put him in the minority until the 1930s.