Haruki Murakami's novels invariably have a theme tune. Norwegian Wood was, most obviously, one of the more brilliantly extended riffs on a Beatles song, but a looping mix-tape featuring phrases and melodies from John Coltrane and Miles Davis (Murakami used to run a jazz club with his wife) as well as snatches of Springsteen and Nat King Cole and Liszt and Grieg provides the musak for nearly all of his writing. Murakami's devoted army of fans spins out long blog threads about the precise meaning and placement of this soundtrack (though most of the time the choice seems obvious enough). The song that rattles most often in the pages of 1Q84 is the old Harburg and Arlen standard "It's Only a Paper Moon", which provides the novel with its epigraph:

"It's a Barnum and Bailey world

Just as phoney as it can be

But it wouldn't be make-believe

If you believed in me"

The song runs in the heads of the two characters through whose stories much of the 1,000 pages of the two-volume "trilogy" (books one and two are one book) is told, in alternating chapters. As the narrative develops in its improvisatory way, the quoted lyrics become a pointed kind of challenge both to them, and to the reader. The particular Barnum and Bailey world into which we and those characters have been cast is Murakami-land, and as always in his fiction it is a place where nothing is ever quite in tune.

The protagonists find their entrances, in different ways. Thirty-year old Aomame is grid-locked in a cab at the book's opening, on an elevated section of the Tokyo Expressway. She's listening to Janácek's Sinfonietta on the car's stereo and daydreaming about how that particular piece of music, written in 1926 in Czechoslovakia, represented the ultimate calm before the storm, a brief peaceful respite in central Europe that served to prove "the most important proposition in history: 'At the time, no one knew what was coming.'"

Aomame too, has no idea what lies in store, but her looking-glass world is about to be revealed. Her driver advises her that if she is to make the very important date for which she is late, she might use an emergency iron stair off the high carriageway that will take her down to ground level. But beware, he suggests, "things might look different to you down there". He's not wrong.

"Down there" is that curious interiorised urban landscape where life has the atmosphere of an air-conditioned shopping mall or an all-night garage or a soundless television watched in a gym; the place, not dissimilar from our own world, though vaguely and surreally dehumanised, in which Murakami's characters are always fated to dwell. Aomame descends and notices the changes of key slowly: policemen's uniforms look a bit different; there are, she could swear, two moons in the sky (one of them perhaps made of paper); and it turns out she is a trained killer – her date is with a man she is to murder in a hotel room. This fact comes as a surprise to us, and possibly even to her.

For all his dislocating effects, Murakami's plot lines – like those of the songs that accompany them – tend to be driven by the simplest boy-meets-girl love stories. Aomame's strangely passive life, in which she administers death to her victims with a single sterile needle applied to a point at the base of the brain, is only given purpose, we come to learn, by the memory of a single act of affection. As a 10-year-old, bullied and ignored by her schoolmates, she once held the hand of a boy in her class, and though circumstances dictated that she hasn't seen the boy in the 20 years since, that moment of innocent intimacy has sustained her forever. That boy, Tengo, through whose eyes the alternating chapters are told, is now a part-time maths teacher and failing novelist, and happily he shares that memory of Aomame, though he has no idea what has become of her, and how fate (or fiction) might reunite them.

Again it is worth pointing out that in Murakami-land there is nothing new under the sun and that this is a kind of virtue. His novels are self-conscious variations on a theme. The author has dwelt on this particular "I want to hold your hand" moment many times. In his 1999 novel, South of the Border, West of the Sun, for example, his boy and girl, Hajime and Shimamoto meet after school to listen to Duke Ellington's "Star-Crossed Lovers" and their destiny is sealed when she momentarily places her hand in his: "It was merely the small, warm hand of a 12-year-old girl, yet those five fingers and that palm were like a display case crammed full of everything I wanted to know – and everything I had to know…" Fate abruptly separates them; you know the rest.

And of course you know the rest here, though the interlude and the extended machinations by which Murakami eventually gets his young lovers back together in Book Three possibly threatens some kind of Guinness record for coitus postponed. In the course of 900-odd pages of riddling foreplay, many more familiar themes are explored. Reality, blurred by myth ancient and urban, refuses to be quite a process of cause and effect; identity is always threatening to dissolve. We may be in a parallel world; it may be just that all our individual worlds are parallel. This solipsism is both prized and the cause of much of the unease. In some senses IQ84 is a distinctly Japanese response to Orwellian themes of unseen power and subjugation of the individual (the novel is set in 1984; the Q is a visual pun on the Japanese character 9 that is, somewhat fittingly, lost in translation).

The more disturbing and authoritarian elements of the world Murakami describes can seemingly be traced back to a commune or cult, which, a generation on, affects the lives of his characters in oblique and submerged ways. Tengo discovers some of the implications of it through the words of a 17-year-old girl called Fuka-Eri, who has written a strange confessional memoir of her former brainwashed life, paranoid about the ubiquitous "Little People" and in thrall to a shadowy "Leader". Tengo, initially intrigued and seduced by Fuka-Eri's weird coldness, reluctantly finds himself taking on the job of rewriting her book, and his version of Fuka-Eri's memoir becomes a literary sensation in Japan.

Murakami no doubt draws some of his own understanding of the world Fuka-Eri hints at from his research into the Aum Shinrikyo cult responsible for the gas attack on the Tokyo subway that was the subject of his non-fiction book Underground. His default setting as a writer lies in documenting a muted alienation – Kafka with an iPod – and solace, in his books, tends to be found in the sudden human connection of sex and longing, but mostly his characters, like his readers, are left to figure things out on their own with shifting and partial information to go on.

As this bleak fairy tale unfolds, lacking contours except the constant promise of a happy ending, a different kind of music from the usual Murakami riffs seems to assert itself. The book, or books, arrive with a trumpet-blast fanfare: a million copies sold overnight in Japan, late-night bookshop openings promised to satisfy worldwide demand, Harry Potter style. Murakami, now 62, has ceased being a novelist and has entered the dangerous world of literary phenomenon, a cult figure himself. None of this should affect the book itself, of course, except that the writing sometimes seems half-conscious of its advance noise, believing the hype. In its overblown complexity and constant arch reference points to other works in the author's canon, it can read like a stubborn effort to write the definitive Murakami, the Great Japanese Novel. While there is generally plenty to keep your foot tapping along the way, the result is that too many notes and digressions feel forced or fall flat.