英語候補area around a red-light district where illegal prostitution occurred (marked on police maps by a blue line; 1940s-1956)
青線あおせん略語blue linearea around a red-light district where illegal prostitution occurred (marked on police maps by a blue line; 1940s-1956)
青線区域あおせんくいきarea around a red-light district where illegal prostitution occurred (marked on police maps by a blue line; 1940s-1956)