The core story is simple enough. Aomame (the assassin) and Tengo (the ghostwriter), both lonely outsiders from damaged backgrounds who are "united by deep wounds to the heart, each bearing some undefined absence", are subconsciously searching for each other, ever since they experienced a moment of connection at school when they were ten years old. Their parallel, carefully interlinked stories, set in Tokyo, unfold in alternate chapters, with the equally outcast investigator Ushikawa introduced into the narrative mix in Book 3. This structure makes for some occasionally wearying repetitiveness, with events often described two or three times, but mostly it serves to build up the momentum, slowly and hypnotically nudging the separated lovers — if you can call them that — closer to each other in a world that "has a serious shortage of both logic and kindness". 

Thus, through the slow-moving, labyrinthine plot and the two parallel narratives, we are made to live through just how vast "the distance that separates one person's heart from another's" can be, even though the central message resounds loud and clear — love conquers all. For despite Aomame's steely alienation, as she takes one life after another, at her core "there is not nothing", just as Tengo knew that "he would find the path he needed to take — as long as he did not forget this warmth, as long as he did not lose this feeling in his heart". This is fantasy too, you might say, and of course it is, but it provides a vital counterpoint to the bleakness of much of the novel.

Over the years there has been a lot of debate in Japan and beyond about Murakami's cult status as a writer — is this serious literature or pop fiction? It's not really a question that needs asking any more, although there are definitely a few too many references to tight skirts, pert breasts and Charles Jourdan high heels, which, along with a heroine who in her superwomanly fitness could have stepped out of a comic, make the shallowness alarm bells ring. But there are also many much richer seams, such as the all-pervading beauty of the pared-down language, the well-chosen imagery and the deep sense of loss, as well as the memorable portrayal of flawed characters such as Tengo's father and his gradual slipping away from life, his death like a "windless day at the end of autumn, when a single leaf falls from a tree".

And this is where Murakami's greatness lies — no matter how violent and fantastic his plots, the underlying themes circle around our fundamental dilemmas, in this case probing not just our quest for love in its full urgency, but exploring just how helpless we are when it comes to knowing anything for sure about the world we live in, it being "an endless battle of contrasting memories". There is also a real engagement with topics such as the treatment of Koreans on Sakhalin Island at the end of World War II, the consequences of domestic violence and the brain-washing power of cults, "foot-binding for the brain" (a subject Murakami also explored in Underground, his collection of interviews with the victims and perpetrators of the Aum Shinrikyo cult's Sarin gas attack on the Tokyo subway in 1995).

So for all its fantasy surface and sexy detail, this is a work of considerable and haunting complexity, which is likely to resonate a long time after one has stopped turning its numerous pages-and don't expect any easy solutions to the existential conundrums raised. As Murakami put it in an interview with John Wray in the Paris Review, back in 2004: "I always hope to position myself away from so-called conclusions. I would like to leave everything wide open to all the possibilities in the world."