Japanese salarymen interrupted their morning commute to buy Haruki Murakami's new novel Friday, as papers and broadcasters raced to give the first review of one of the most awaited books of the year.

Stores opened early in Tokyo, with special stands stacked high with the hardback books, as businessmen, housewives and students rushed to get a copy.

The new novel, "Shikisai wo Motanai Tazaki Tsukuru to Kare no Junrei no Toshi (Colorless Tsukuru Tazaki and His Years of Pilgrimage)", was unveiled to a dedicated band of followers at midnight.

More than 100 excited "Harukists" flocked to Tokyo's Daikanyama T-Site bookstore, which flung open its doors at exactly 12 am.

Sanseido bookstore temporarily became "Murakami Haruki-do (store)", installing a new name board to mark the release of the eagerly awaited novel.

Fans were told virtually nothing about the book ahead of the release, adding to the mystique of an author who delights in setting riddles for characters and readers alike.

A skim reading of the work by an AFP journalist reveals it is the story of a young man struggling with an ordeal in his past, who uses the support offered by a romance to get back on his feet.

The mass-circulation Yomiuri Shimbun managed a short article on the 370-page book in its later Friday morning editions.

Breakfast television programmes showed journalists who had been at their desks all night reading.

"It's gripping," said one NHK reporter, adding he was mid-way through.

The Asahi Shimbun posted what it called a "super-quick" review on its website at 7:46 am.

"This is a story about a man who tries to get back into his life again," the review said.

"You see the strength of a person who tries to overcome the feelings of loss and loneliness that he had amassed deep inside of himself," the Asahi said.

The book's cover -- featuring American artist Morris Louis's "Pillar of Fire" -- was also the subject of hot debate on the micro-blog Twitter.

Ryosuke Kawai, 26, who was one of the first to get his copy at the midnight event said he had been caught off guard by the cover of the book, a painting involving colourful stripes.

"The title says 'colorless'. What does this illustration mean? I cannot wait to read it," he said excitedly.

Some observers had speculated the title may be a deliberate echo of a collection of piano pieces called "Years of Pilgrimage" by Hungarian composer Franz Liszt.

Twitter users praised the author for the excitement he had been able to engender with the book, in a nation of people hooked on smartphones and videogames.

But there was also something of a backlash against the secrecy, dismissed as little more than a marketing ploy for an author whose works often explore alienation among characters with specific quirks.

One Twitter user complained that even without reading the book he knew what it would be about.

"I know the story already. It's about a man who is smart but lonely without friends but somehow attracts women and makes spaghetti," he said.

Murakami's most recent work, the three-part "1Q84", baffled and delighted readers with its parallel universes in which the lives of a female murderer and a male novelist intertwine.

"1Q84", which can be read as "1984" in Japanese -- a deliberate nod to George Orwell's dystopian tale -- proved a worldwide phenomenon, with the last installment published in Japanese three years ago.

Murakami's novels, which have drawn international acclaim and been translated into around 40 languages, include "Norwegian Wood", "Kafka on the Shore" and "The Wind-Up Bird Chronicle".