TOKYO (AFP) – A group of Japanese women filed a challenge Monday to a 19th century law that compels almost all females to drop their maiden names and assume their husbands' surnames when they marry.

The landmark case, launched before the Tokyo District Court, is seen as a test for the rights of women, who continue to struggle against gender stereotypes and remain under-represented in politics and corporate boardrooms.

Japan's Civil Code stipulates that married couples must share one surname -- in practice almost always that of the husband, although some men have assumed their wives' names, often if the women come from noble families.

The plaintiffs -- four women, and the husband of one of them -- argue that the civil code clause dating back to 1898 breaches the constitutional guarantee of equal rights for both spouses.

The individuals from Tokyo, Kyoto and Toyama are also demanding a total of six million yen ($70,000) in damages for their emotional distress.

One of the four women, Kyoko Tsukamoto, 75, said that having been forced to use her husband's name officially for more than half a century was "like having a splinter in my heart".

"I want to die as Kyoko Tsukamoto," said the retired school teacher who uses her maiden name for private purposes but must use her husband's surname, Kojima, on legal documents.

The woman, of Toyama in central Japan, said her husband disagreed with her desire to revise their marriage certificate but that she joined the legal action after lobbying lawmakers in vain for decades for a change in the rules.

"I'm happy to file the lawsuit together with my companions who have the same ambition," Tsukamoto told a news conference.

"It's going to be a long fight. Please help us."

Public opinion in Japan is sharply divided on the issue. In a recent government survey, 37 percent of respondents said they supported a revision of the civil code, while 35 percent were against.

Hopes for a change rose after the centre-left Democratic Party of Japan (DPJ) took power in September 2009, ending more than half a century of almost unbroken conservative rule, and pushed for an immediate change.

However the reform withered as the DPJ's small coalition partner, the People's New Party, strongly opposes the move, a position shared by many other conservative politicians in Japan.

"Disappointment has prevailed," said Fujiko Sakakibara, a lawyer for the plaintiffs. "We had high expectations from the legislative process, but it did not work out. Now, there is no choice but to go to court."

The first hearing is likely to take place several months from now, lawyers said, adding that they had chosen Monday as the day to file the lawsuit to coincide with St. Valentine's Day.

Other plaintiffs also spoke of how badly they felt about having had to give up their maiden names.

"It's like losing part of my self," said Kaori Oguni, who married five years ago but privately uses Oguni as her family name.

"Marriage is supposed to be joyful... but I guess quite a lot of people feel agony about losing their names."

"I have a one-year-old daughter. I don't want her to have the same feeling," said Oguni. "I'm feeling that we have no choice but to appeal to the courts to break free from this discrimination."