national of a third country
Neutral legal/diplomatic term for a person from a country other than the two directly involved in a bilateral context. Not inherently derogatory.
This agreement also protects the rights of nationals of third countries.
foreign resident in Japan (esp. Chinese and Korean)
Historically used in post-WWII Japan to refer to former colonial subjects who remained in Japan. Now considered sensitive and potentially discriminatory; avoid in modern neutral contexts.
After the war, people referred to as 'third-country nationals' faced various hardships.
The expression '第三国人' is now often regarded as discriminatory.