Koreans in Japan are the ethnic Korean residents of Japan. They currently constitute the second largest ethnic minority group in Japan. The majority of Koreans in Japan are Zainichi Koreans, also often known as Zainichi (在日) for short, who are the permanent ethnic Korean residents of Japan. The term "Zainichi Korean" refers only to long term Korean residents of Japan who trace their roots to the period of Japanese colonialism in Korea, distinguishing them from the later wave of Korean migrants who came mostly in the 1980s.
The Japanese word "Zainichi" itself means "staying in Japan", and implies temporary residence. Nevertheless, the term "Zainichi Korean" is used to describe settled permanent residents of Japan, both those who have retained either their Joseon (old, undivided Korea) or South Korean nationalities, and even sometimes includes Japanese citizens of Korean descent who acquired Japanese nationality by naturalization or by birth from one or both parents who have Japanese citizenship.