Ladbrokes with 5/2 odds.
Also near the top of the Ladbrokes list is Canadian Alice Munro with odds of 4/1, and American Joyce Carol Oates with 8/1 odds.
Murakami has impressed the critics and won a mass readership with his intricately crafted tales of the absurdity and loneliness of modern life. His works, which are peppered with references to pop culture, have been translated to around 40 languages.
Munro is a writer of short stories, a genre that has only rarely been recognised by the Nobel committee, while Oates can look back at a prolific career spanning five decades during which she has produced more than 40 novels as well as plays and poems.
Overall, however, there is little consensus about who will win the prize, worth eight million Swedish kronor ($1,25 million, 925,000 euros). Observers also point to Belarussian writer Svetlana Alexievich and Algerian Assia Djebar as possible laureates.
The winner's identity will be revealed at 11 GMT Thursday, when the Swedish Academy, picking as its venue the historic Bourse building in downtown Stockholm, will announce the winner of the world's top prize for literary excellence.
A total of 195 authors have been nominated, including 48 first timers, and that is pretty much all that is known beforehand.
The deliberations of the Swedish Academy are secret and will remain closed to the public for the next 50 years, but outsiders still have some inkling of the factors that guide them -- and literary fame is not among the top concerns.
"For the past 15 years, the Academy has... explored questions of literary quality, the evolution of literature, and its place in a historical context. It's fascinating work," said Gunilla Kindstrand, editor-in-chief at Swedish newspaper Haelsingetidningar.
"For them, it's less important if the laureate is well-known or not."
Or, as prominent Swedish publisher and journalist Svante Weyler put it: "The Academy takes a certain pleasure in surprising people, and acts in a slightly irrational manner."
After last year's prize to Chinese writer Mo Yan, whose close ties to authorities in Beijing made him controversial, the Academy has two choices this year, he said.
Either it can pick a writer who is completely apolitical, or it can choose one who is politically engaged, but not in a way that upsets the West.
"Svetlana Alexievitch fits that description perfectly," he said.
This opinion is shared by Bjoern Wiman, culture pages editor for Swedish daily Dagens Nyheter.
"The Academy ought to have recognised literary reporters in the Ryszard Kapuscinski class a long time ago," he said, referring to the celebrated Polish foreign correspondent and writer, who died in 2007.
"Alexievitch is a documentary author who writes polyphonic reportage at a very high level of accomplishment."
He added that he believed very firmly this year's prize would go to a female writer, something that has only happened 12 times since the award was first handed out in 1901.
Among other names that keep popping up: Poets Ko Un of South Korea and Syria's Adonis, as well as novelists including American Philip Roth and Albanian Ismail Kadare.
It's not essential that the winner has "written a lot of books", argued students at Rinkebyskolan, a school in a disadvantaged neighbourhood of Stockholm which traditionally receives a visit from the literature laureate every year.
"The books have to be good, that is to say interesting and a source of inspiration, and they should motivate people to do something good for mankind," a group of students from the school told AFP in an email.
Whether the 2013 winner fits that bill will remain a mystery for a few more days. For Weyler, the publisher, the only thing that is beyond doubt is the likely age of the laureate.
"In literature, you are rarely very good until you get old," he said jokingly. "It's not like mathematics where you make all the discoveries before the age of 25."
Swedish poet Tomas Transtroemer, who won the prize in 2011 at age 80, argued that "for most writers, the Nobel Prize is a very distant phenomenon. Even though literary prizes can spur on writers, there are other forces that motivate a work."
The winner will receive the prize in Stockholm on December 10, the anniversary of the death of Swedish industrialist and philanthropist Alfred Nobel, who established the award.