Akasen

Akasen (赤線) was the Japanese slang term for districts historically engaged in the sex work industry in Japan, specifically within the time period of January 1946 through to March 1958.

Etymology
The term literally translates as "red-line". Though similar to another term previously used for red-light districts,, was used as a collective term for red-light districts only between 1946 and 1958, following an issue ordered by GHQ (SCAPIN 642) nationwide to abolish Japan's legalised system of sex work.

Another term, lit. "blue-line"' (青線), was used for "non-permitted" or "non-legal" sex industry districts. In Tokyo, the area directly across the Sumida river from Yoshiwara (Tamanoi, now called Higashi Mukōjima) was a well-known district; it features in some of Kafū Nagai's short stories.

The term is often compared directly with the term "red-light district" in the west. However, this does not explain why the counterpart "non-permitted districts" were known as (blue-line) districts. In practice, and  referred to the colors on municipal zoning maps that outlined brothel districts  and "normal" entertainment districts.

History
The precursor of districts were yūkaku (遊廓), legal red-light districts in Japan where both brothels and sex workers (known collectively as lit. "woman of pleasure" (遊女), the higher ranks of which were known as oiran (花魁)) recognised by the Japanese government operated. In January 1946, GHQ issued an order (SCAPIN 642) nationwide to abolish this licensed sex work system. This had a number of impacts on areas, the largest of which was the  being renamed as "akasen" (赤線) districts. Brothels had to rename themselves as either cafés (カフェ) or ryōtei (料亭), sex workers were no longer bound by state-guaranteed contracts, and all known houses of sex work were declared to have "Off Limits" status by SCAP GHQ. The order also had the effect of disbanding the short-lived Recreation and Amusement Association, which had, for a period of one year, worked to ensure that sex workers were not abused and exploited by stationed American soldiers, amongst other things.

Despite the increased restrictions and the restructuring of the sex work industry, commercial brothels continued to operate within the law, with districts remaining the designated regions for state-regulated sex work. Due to GHQ orders, brothels - often numbering in their hundreds - began to front non-adult faces of their businesses (such as coffee shops, cafés and beer halls), but would offer sexual services to customers, creating new avenues for the sex industry to continue, especially in popular districts such as Yoshiwara, the region of Tokyo.

However, following the partial disbanding of traditional red-light areas, formerly law-abiding sex work businesses began operating within  areas, creating difficulties for the SCAP to identify brothels and continue its "Off Limits" policy.

In 1958, the Anti-Prostitution Law (売春防止法) was enforced, thus officially abolishing legalised sex work, the red-light districts and their label of.

Despite the criminalisation of sex work, by the beginning of the 21st century, businesses such as soaplands (ソープランド) and fashion health (ファッションヘルス) massage parlours had come into existence, regulated under the Businesses Affecting Public Morals Regulation Law Act (風俗営業等の規制及び業務の適正化等に関する法律), also known as Fūzoku Eigyō Torishimari Hō (風俗営業取締法) or. These businesses, which avoid criminalisation through offering only non-coital sex acts, are required to file a license application for permission to abide by the sex industry law (風俗営業法) to remain in operation.