The treatment of Japanese employers in Hawaii and the mainland US was very different. In Hawaii, they were able to keep their businesses largely unmolested, but in the continental US, most would lose their businesses. The Japanese were not expelled, but kept in internment camps until the war ended and would not be paid for their economic losses by until the 1970's under President Jimmy Carter when it was found that the internments were based on "hysteria" and "prejudice".
There was concern in Hawaii that the Japanese citizens were involved in code breaking that lead to the attack. The army ransacked their homes searching for evidence but couldn't find any. Wikipedia offers the explanation that the difference in treatment was completely driven by economic concerns. The Japanese were not a small minority in Hawaii at this time, and says: To imprison such a large of a group from the islands would cripple the Hawaiian economy.
In the mainland US, most Japanese lived in California, where there was a long-standing historical prejudice against them. There were segregated schools for them in California, for instance. The rationale for internment in the mainland was a nonspecific concern of possible espionage, which could neither be proven nor disproven. Internments were "voluntary" but strongly coerced. All Japanese in the mainland had their bank accounts cancelled by the US Treasury. Most businesses need banking to operate. They were no longer allowed to own land, which some businesses or "employers" if they are farmer for instance may do. There also would have been horrible discrimination against the Japanese, so any business would have lost many of its customers. So most Japanese lost their property and businesses and entered the internment camps.