noun
Historical term for a designated prostitution district in Japan, especially under the post-WWII system until the 1958 anti-prostitution law. Often contrasted with 青線区域 (illegal/unlicensed districts).
戦後、赤線区域は各地に存在した。
After the war, red-light districts existed in various places.
赤線
The red-light districts were abolished with the enforcement of the Anti-Prostitution Law.