Newly retired engineer Kotaro Toyohara arrives home for a family celebration after his final day at work, clutching a ring for his wife, Yoko, his head full of plans for the years of leisure ahead.

To his shock, Yoko blurts out that she wants a divorce.

That was the scenario for one of this season's most popular Japanese television drama series, "Jukunen Rikon" or "Mature Divorce", reflecting a phenomenon that many commentators fear may balloon as Japan's baby-boom generation heads into old age.

"Women are becoming more independent. When their husbands retire, they realize they have 20 or 30 years of life ahead of them and they don't want to carry on as before" said Atsuko Okano, who runs Carat Club, a divorce counselling service. With a new law set to come into force in 2007 allowing ex-wives to claim half their husband's pension, domestic media are warning of a possible divorce boom.

The number of Japanese couples parting ways has risen rapidly over the past 20 years to a 2002 peak of 290,000, while divorce among those married more than 20 years has increased even faster.

Some Japanese women see their husbands as an obstacle to enjoying their sunset years.

With few hobbies or friends to turn to, many Japanese retirees, often nicknamed "wet leaves" for their tendency to cling to their wives, spend their time at home. They expect their spouses to wait on them as they did when they were bread-winners.