Choosing Valentine's Day to make a heartfelt statement, gay couples will file the first-ever lawsuits in Japan challenging the constitutionality of not recognizing same-sex marriages.

The plaintiffs in the group suits are 13 same-sex couples who reside in Tokyo and seven other prefectures and range in age from their 20s to 50s.

The lawsuits will be filed at four district courts in Sapporo, Tokyo, Nagoya and Osaka on Feb. 14.

“A country that does not recognize a gay marriage as legal amounts to branding same-sex couples as a ‘union not approved by society,’” said Takako Uesugi, who will co-lead the legal team in the lawsuit in Tokyo. “We would like to restore the dignity of people who love their partners of the same gender.”

A team of lawyers representing the plaintiffs will argue that it is unconstitutional for the central government not to allow same-sex marriages as it infringes on the freedom of marriage and equality under the law, guaranteed in the nation's Constitution.

They will demand 1 million yen ($9,000) per plaintiff in damages on the basis of the State Redress Law, contending that the Diet has failed to revise the Civil Law and other relevant legislation to allow same-sex marriages.

The Civil Law, which was put into force in 1898, does not have a clause forbidding same-sex marriages.

However, public offices do not recognize gay marriages as legal even if the partners try to list them in their family registers on the grounds that the Civil Law and the Family Registration Law presuppose that marriage is between a man and a woman.

According to the Equal Marriage Alliance, a Tokyo-based nonprofit advocate of the legal recognition of same-sex marriage in Japan, 25 countries and regions recognize gay marriages.

Japan is the only country in the Group of Seven industrialized nations that does not provide gay couples with the legal protections afforded to married couples.

Italy, where the Catholic Church that has long deemed same-sex marriages as taboo maintains a dominant presence, moved to recognize same-sex couples as having rights equal to married couples in 2016.

Asami Nishikawa and Haru Ono of Tokyo’s Setagaya Ward are among the couples who will join the group lawsuit.

The women, who are in their 40s, were notified by the ward office on Feb. 12 that their marriage could not be registered on the grounds that it is “unlawful.”

Nishikawa has been hoping to take the issue to court after learning of a wave of lawsuits filed in the United States and across Europe demanding the legal recognition of same-sex marriages.

“There are a large number of same-sex couples in Japan who have built their relationships as longtime partners, have lived as members of a local community and wished for the restoration of their dignity,” she said.

Nishikawa and Ono have lived together for 14 years. Both have children from previous marriages to men. The couple lives with two high school-age children.

But under the law, their union is not considered legal, and they do not have joint custody of their children.

The couple has lived in constant anxiety about how to describe their relationship to people in their community, in their workplace and their children’s schools.

Their desire for legal recognition of their “marriage” became stronger when Ono underwent breast cancer surgery in 2016.

Ono was worried whether Nishikawa would be allowed to be at her side when her doctor discussed her condition and sign the consent form for her surgery as her partner.

Those experiences made her realize that the traditional system of marriage provides layers of legal protection for couples, which she did not realize while she was married to a man.

If their marriage is not legalized, her partner cannot legally inherit their property. No legal responsibility rests with her partner to raise her child after her death, either.

“Many lesbian, gay, bisexual and transgender couples raise their children in not only large cities, but also the countryside,” said Ono, who heads Nijiiro Kazoku (Rainbow-colored families), a group of sexual minority families who hope to form a loose network of assistance. “We live in a society where families of diversified backgrounds live, and I would like the public to become aware of this reality.”

But the central government, led by Prime Minister Shinzo Abe, and his Liberal Democratic Party, are reluctant to legally recognize gay marriages.

Instead, a majority of LDP lawmakers have championed the traditional concept of a family being a man and a woman with children.

In a 2016 party brochure, the LDP made clear its opposition to same-sex marriages.

However, the Constitutional Democratic Party of Japan, the main opposition, is preparing a revision bill to legalize gay marriages.

Local governments have already moved to start a new “partnership system” initiative, which calls for offering consideration to gay couples by issuing them “partnership certificates.”

One local service that this certification makes them eligible for is public family housing.

Tokyo’s Shibuya Ward became the first such local government in the nation in 2015 to offer the certificates to same-sex couples, which was followed by the capital’s Setagaya Ward.

So far, 11 local governments have introduced a similar system, including Sapporo, Fukuoka, Osaka and Chiba.

Another couple in Tokyo who will join the lawsuit, Ikuo Sato, 59, and his partner in his 50s, are praising the tide in Japan that is turning in support of same-sex couples.

When Sato and his partner filed their “marriage papers” in a local government office in January, they received a card saying, “Congratulations on your marriage,” just as a male-female couple would.

“When I was young, I gave up on being recognized (as married to a same-sex partner),” Sato said. “But I want to show young people that society is changing.”

(This article was written by Satomi Sugihara and Yuki Nikaido.)