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Despite its antiquated appearance , the Ki-2 was successfully used in Manchukuo and in north China during the early stages of the Second Sino-Japanese War , in areas where danger from enemy fighter aircraft was minimal .
 Manchukuo
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Manchukuo