青あお線せん区く域いきMeaningsNoun1. area around a red-light district where illegal prostitution occurred (marked on police maps by a blue line; 1940s-1956) (Historical)Kanji used青blue線line区district域regionComposed of青あおblue; azure; green; green light (traffic); black (horse coat color); blue 5-point card; immature; unripe; youngNoun線せんline; stripe; stria; line (e.g. telephone line); wire; ray (e.g. X-ray); beam; line (e.g. of a railroad); track; route; …Noun区く域いきarea; zone; district; quarter; section; limits; boundaryNoun