Japanese writer Haruki Murakami.

Japan must say it's sorry repeatedly to China and the other countries it invaded in the 20th century until its former victims have heard the apology enough times, according to novelist Haruki Murakami.

"The issue of historical understanding carries great significance, and I believe it is important that Japan makes straightforward apologies," he told Kyodo News in an interview in Tokyo.

"I think that is all Japan can do－apologize until the countries say, 'We don't necessarily get over it completely, but you have apologized enough. All right, let's leave it now'."

Murakami, one of Japan's best-known writers who has been repeatedly predicted as a future Nobel Literature laureate, has often chided his country for shirking responsibility for its aggression in World War II.

His remarks come as the world watches what Japan's conservative Prime Minister Shinzo Abe will say in a statement expected to mark the 70th anniversary of the end of the war this summer.

Observers are focusing on whether Abe will make direct reference to Japan's "colonial rule and aggression" and express an "apology", as previous premiers did on the 50th and 60th anniversaries.

Abe, a strident nationalist, wants Japan to have what he says is a less masochistic view of its history, but has caused waves by quibbling over the definition of "invade" and has provoked anger by playing down wartime sex slavery.

Tokyo is lambasted regularly by Beijing and Seoul for a perceived failure to atone for the past, and for being unwilling to "face history squarely".

Without referring directly to Abe or his upcoming statement, Murakami said, "Apologizing is nothing to feel embarrassed about."