KYOTO, Japan (AP) -- Japanese author Haruki Murakami said his latest novel was a new experiment and grew longer than expected as he developed a desire to expand on side characters while writing.

The latest novel by one of Japan's most respected and popular novelists, "Colorless Tsukuru Tazaki and the Year of His Pilgrimage," has sold more than 1 million copies a week since it went on sale last month.

Murakami said that the novel reflects his deep interest in real people and relationships rather than allusions.

The novel is about a man who had been suddenly rejected by his close friends and his process of healing from that.

"At the beginning, I was planning to write something allusive, as in my past works. But this time I developed a great interest in expanding on real people. Then the characters started to act on their own. I was intrigued by the relationships between people," Murakami said.

Murakami said the significance of storytelling is to portray something invisible and deep inside in each person and help create a place where people can sympathize and identify with others.

"If a reader sympathizes with my story, then there is a network of empathy," he said.