"I'm glad I did it, but it was a little bit early," the 85-year-old laughed in a recent interview in the ancient capital of Kyoto. "It was a bit of a waste. I had no idea I was going to live so long. I thought it would be 25 years at most."

Not that she spends her days in solitary contemplation.

A prolific writer, who also preaches and makes frequent television appearances, she is in huge demand on the lecture circuit as an expert on the 11th century epic romance The Tale of Genji, which is celebrating its 1000th anniversary this year.

"Usually people who do bad things make good writers," she said in a February lecture at a Kyoto hotel. "I did a lot of bad things, which is why my novels are interesting."

Born on Shikoku, the smallest of Japan's four main islands, Setouchi led a conventional life until her mid-twenties, when she left her husband and child after starting an affair with a younger man. She later had a lengthy affair with a married man.

"The most important thing to write about in novels is love affairs," she said. "Corporations and politics – none of that is interesting."

Setouchi gradually built up a literary reputation, winning prizes and the stamp of respectability in the form of an award from Emperor Akihito following her translation of "Genji" into modern Japanese, which succeeded in bringing the classic to a wider audience.

What she enjoys most now is to work on her novels, self-help books and religious texts, all written long-hand with a fountain pen in the traditional vertical style.

"I'd like to learn to use a computer, but I just don't have the time," she said, adding that she had slept only two hours the night before.

Setouchi is now so popular as a preacher that fans enter a lottery to attend events at a hall built on her land, while up to 15 000 gather to see her speak at another temple in Iwate in northern Japan.

Though usually seen dressed in the simple robes and white socks associated with her vocation, Setouchi's personality shines through in her infectious laugh and love of the new – she travels widely and taps out text messages on a mobile phone.

"She's not really like a nun," said one long-term associate. "She eats meat, she drinks and she writes novels. Her roots are in anarchy."

Setouchi says that may be the key to a healthy long life, something her admirers often ask about.

"I do what I like. I think illness comes from stress," she said."