The status arose following the end of World War II, when many Koreans lost Japanese nationality.
However, their Japanese citizenship was later revoked by Japanese government after Japan surrendered and gave up sovereignty over Korea, first practically in 1947 under Edict of Foreigner Registration (ja) of Allied Occupied Japan, then finally and formally, in 1952 through the San Francisco Treaty.
Hence, the Koreans who then resided in Japan were registered as "of Chōsen" according to their geographical origin as substitution of nationality.
[1] Some Chōsen-seki individuals report discrimination based on their status, as it is associated with North Korea.
"[6] On September 30, 2010, the Seoul High Court declared that an ethnic Korean from Japan with Chōsen-seki status was a "stateless overseas compatriot" and could be refused a travel document; on appeal in 2013, the Supreme Court did not use the term "stateless" but suggested that the individual was not a South Korean national.