Novelist Junichi Watanabe, a writer who favored love stories depicting extramarital affairs, died of prostate cancer Wednesday at his home in Tokyo, his family said Monday. He was 80.

The orthopedist-turned-writer, a native of Hokkaido, won the Naoki Prize for popular literature in 1970 for his novel "Hikari to Kage."

Watanabe wrote a number of love stories in the 1980s, and his 1997 novel "Shitsurakuen" ("Paradise Lost") about a middle-aged couple having an extramarital affair became a best-seller with more than 2.5 million copies flying off the shelves.

Many of his works were adapted into movies and a museum in Sapporo is dedicated to him.