Now just how'd all this get started?
Some history
This whole story really begins with a different series altogether. Takachiho Haruka had begun working on space adventure stories while still in high school in the 1960s, his ideas influenced by Japanese and American science fiction stories in print, movies, and television. After finishing college, he, together with the animator Yasuhiko Yoshikazu and others, many of whom he met at a science-fiction convention, founded Studio Nue (named for the Japanese analogue of the Western mythical chimera -- "an impossible studio doing impossible things" as Takachiho puts it). The group set to work on developing ideas for stories to appear eventually in print, in manga, and in animation.
Takachiho's own debut in 1973 was with the novel Wakusei Pizan no Kiki <Crisis on Planet Pizan>, the first of the Crusher Joe novels, a series which would eventually extend to twelve books.* The stories are in the broad, swash-buckling adventure style known as "space opera". The Crushers are an organization initially involved in the for-profit business of terraforming, clearing the Galaxy for colonization; in the course of time, though, they branch out into trouble-shooting more human-scale problems for hire, dealing with space piracy and the like. Initially, the Crusher Joe novels were unfashionable, something which changed with the appearance of Star Wars in Japan in 1978.
*After retiring the Crusher Joe series around 1990, Takachiho has returned to it with new novels published in 2003 and 2005.
It is important to our story to mention that Takachiho counts martial arts and pro wrestling among his many interests. It seems that he was receiving a visitor, fellow science-fiction writer A. Bertram Chandler, at the Studio Nue offices in Shakujii, probably sometime in 1978. Somehow it was decided that they would go, accompanied by two Nue staffers named Tanaka Yuri* and Otoguro Keiko, to a World Women's Wrestling Association match [all right, d'ya see what's coming?]. One of the tag teams involved was the popular Beauty Pair. Some unspecified incident moved Chandler to remark to Takachiho at one point something like, "Those two up there [in the ring] may be the 'Beauty Pair', but the two with you ought to be called the 'Dirty Pair.'" This gave the writer an idea for a story.
*Tanaka-san later married Takachiho's brother.
But it wasn't quite that simple, apparently. Takachiho's editor wasn't much taken with the idea, pointing out that, up to that time, no series in print, in cinema, or on television that featured two female lead characters had ever enjoyed success in Japan. The author went home to give the matter some thought (perhaps in the bath, where he has said he's gotten some of his best ideas). His solution was to give the two protagonists strongly contrasting personalities: one calm, polite and reserved (at least outwardly), the other aggressive, sharp-tongued and quick-tempered.
The Dirty Pair novels are a hybrid of "hard" science fiction (Takachiho was influenced, as were many Japanese science fiction and fantasy writers of his generation, by American works of the 1950s and '60s) and "hard-boiled" detective stories. This is actually in keeping with a long-standing tradition in Japanese science fiction publication. The magazine Shinseinen <New Youth>, started in 1920, became the major vehicle for tantei shosetsu <detective fiction>. Its editor, Koga Saburo, separated the works into two groups: stories which hinged on the classic solution of a riddle was categorized as honkaku <regular>, while everything else was classed as henkaku <irregular>. So, for some time afterwards, science fiction in Japan appeared under the heading of "irregular detective stories". (This is not too different for what happened in the West. The classic stories of Poe or Conan Doyle establishing the genre of modern mystery were referred to as "scientific detection".)
The tales of the Dirty Pair take place in the same "universe" as the Crushers, about twenty years earlier than most of the Crusher Joe stories, that is, shortly before the birth of Joe.* The very first Dirty Pair story is almost a parody of space opera, being rather light-hearted and establishing the tradition of recklessness, bizarre situations, and large-scale destruction** that are associated with its principal characters. The later novels develop more serious story ideas and are sometimes darker, but continue to maintain a fair amount of humor.
* In the Crusher Joe story continuity, Dan, the founder of the Crushers, marries a woman named Yuria; Joe is born of this union in 2142. Takachiho recently ended years of fannish speculation by declaring that she is not Yuri of the Lovely Angels.
** The climax of the first story involves the fall of a large orbital station, due to the worst possible luck, into the heart of a major city, inspired probably by the uncontrolled descent of the American Skylab in 1978 (an event roughly mimicked by the 2001 controlled re-entry of the Russian Mir).
Takachiho's degree from Hosei University is in the social sciences, rather than in the physical sciences or engineering. His stories are thus often more interested in the characters, their relationships, and the worlds they inhabit than in the details of science and technology. As a consequence, his vision of the mid-22nd Century is relatively conservative technologically, when compared to many other science-fiction writers. If there is a particular theme which recurs in the DP novels, it would be concerned with developments in biotechnology and "artificial life".
It should be said that, on the whole, Japanese science-fiction dotes far less on high technology than does American SF (what has been called the "gee-whiz!" aspect). Writing in 1988, John Apostolou remarked "Surprisingly few Japanese SF writers are genuinely interested in science and technological advances... The future holds no great fascination for most [of them]; instead, they use the genre to examine the past and the present, attempting to understand their rapidly changing society." It is certainly the case that the Japanese have traditionally been more skeptical about change than have Americans; their treatment of science-fictional themes is often cautionary or dark (much as occurred in the American "new wave" of the 1960s or in "cyber-punk").
Something to know about the characters
As Kei lets you know right from the start (she's the narrator of the novels -- are you surprised?), she and Yuri don't have a great deal in common as far as tastes and interests are concerned. Moreover, the differences in their personalities and their outlooks on life and work are a frequent source of friction. Yuri is, to some extent, the embodiment of the classical (which really is to say, aristocratic) ideal of Japanese feminine beauty and also of yamato nadeshiko, which sets certain requirements for the "perfect woman" (it should be pointed out, though, that Yuri does use a certain amount of this as a façade). Kei is then her foil: she is based on a character type introduced into Japanese comedic theater about 300 years ago -- the brash, loud, uncultivated working woman of the rural provinces.
Despite all that, since they met in school seven years before the time of the first four novels, they have been inseparable. What would make them decide to stick together?
They had discovered accidentally, about five years before we meet them, that they share a psychic gift of clairvoyance. It permits them to see visions of things that turn out to be vital clues to mysteries; however, these apparitions are generally vague and offer no immediately clear meaning to the two of them (unlike, say, the free-lance investigator Frank Black in Chris Carter's Millenium TV series, whose visions usually did convey clear details of circumstances surrounding a case). Moreover, they can only receive these clues by making physical contact: they are incapable of conjuring up these images individually. The Lovely Angels, to use their operatives' codename, are referred to as an "ESPer team." Their special ability is what got them their job with the WWWA and has led them to achieve a spectacular success rate in unraveling criminal mysteries.
There is, um, one other little thing to be aware of -- perhaps the price they pay for their gift: they are surrounded by the most abominable sort of luck. When the situation of the moment gets out of control (which it frequently does, usually through the actions of the villians), the results are devastating to both their adversaries and innocent bystanders. Simultaneously, the timing of events manages to work out so as to permit them to escape with their skins intact. Naturally, those not privy to the details conclude that these two women investigators are at best a jinx, at worst an active menace. During their first year of employment, the Lovely Angels had already acquired their Galaxy-renowned sobriquet, the "Dirty Pair." (There, I said it...)
Their birthdates, given in the chronology below, do not seem to be completely arbitrary. Upon investigation, it appears that Kei and Yuri strongly embody Sagittarian and Piscean personalities in Western astrology and those of Snake and Horse in Chinese astrology (discussed further in Signs and Portents).
As may be clear from the origin of the story concept, the design of the Angels' silver uniforms, by Yasuhiko Yoshikazu, is derived from women's wrestling attire and the fashions of the 1960s, especially that era's vision of futuristic garments. (The story of Yasuhiko's involvement is interesting. When Takachiho first approached him to illustrate his stories, "Yas" protested that he was an animator and had little experience with doing static art. Takachiho persisted, though, and after a few days, Yasuhiko relented. He ultimately went on to illustrate all of the Crusher Joe and Dirty Pair novels, right up to the present day.)
(left) the first collection of Yas' illustration work, published back in 1981
(right) a more recent collection, published in December 2000; the title is something of a misnomer, since one volume couldn't begin to do the job of covering Yasuhiko's roughly thirty-year career; it is largely a compilation (beautifully printed) of his color paintings for his own series, a few others (I'll particularly note DP, of course), and some commercial work [click on cover to see some paintings not shown elsewhere in this Novels section]
There were also two CD-ROM collections of his work released in 1994 and 1997, which are rather harder to come by...
A retrospective exhibition of Yasuhiko's work, "Yasuhiko Yoshikazu's World", has been touring Japan since the spring of 2006; a detailed report with images can be found here
Story chronology
early 2110s FTL propulsion developed
2110s to 2130s explosive human colonization of extrasolar planets: some 3000 planets will be inhabited by 2141
27 November 2121 Kei born at Nioghi colony (Note: the date is given erroneously as 27 December in the David Lewis translation, Great Adventures of Dirty Pair)
18 March 2122 Yuri born at Yocha colony
2130s extrasolar colonies break away from Federated Terra
2134 United Galactica (UG), the confederation of free "planet-states", founded; Kei and Yuri meet at the University of Mezuil
2135 founding of the Worlds' Welfare Work Association* (the WWWA, more frequently referred to as "3WA"), a sort of cross between a United Nations agency, a consultancy firm, and a private detective outfit, aiding UG-member planets, by commission, with difficulties of world management and operations; the Association offers assistance in terraforming, agriculture, economics, political science and planetary administration, criminal investigations, etc.; contrary to many people's impressions, it is neither a police nor a military force (matters of warfare are handled by the United Space Force); the 3WA has no jurisdiction over the internal affairs of a UG-member planet
* the name in kanji is Sekai Fukushi Jigyou Kyoukai, but nobody calls it the SFJK
2136 Yuri and Kei discover their collective psychic ability
2139 the two women graduate (with unremarkable academic records) from University and are recruited by the WWWA
2139-40 they undergo intensive training at the WWWA facility on Shimogu, followed by promotion to criminal investigations division trouble consultants; time of the side story, Dokusaisha no Isan
2141 time of most of the novels
...
2294? time of the fifth novel
As they say, the rest is (the end of) History...