noun
Historical term for a red-light district, so called because such areas were marked with a red line on police maps. Refers to the system in place from 1946 to 1958.
戦後の赤線地帯は、現在の法律では存在しない。
The post-war red-light districts no longer exist under current law.
Refers to areas marked with a blue line on police maps, indicating illegal but tolerated prostitution zones, distinct from the officially recognized red-line districts.
From 赤線 (red line) + 地帯 (zone, area), referring to the red lines drawn on police maps to designate legal red-light districts in post-war Japan.