Photo/IllutrationPlaintiff Yoshihisa Aono, left, and Tomoshi Sakka, an attorney representing the plaintiffs in their lawsuit filed in Tokyo District Court, hold a news conference in Tokyo's Kasumigaseki district on Jan. 9. (Ryota Goto)

A married man filed a lawsuit in Tokyo District Court on Jan. 9 claiming that the current law prohibiting married couples from using different surnames is unconstitutional.

Yoshihisa Aono, 46, filed the lawsuit along with three other plaintiffs, who all live around Tokyo, demanding the government pay 2.2 million yen ($19,541) in damages. They claim that the Family Register Law, which allows Japanese-foreigner couples to choose different surnames but not Japanese couples, violates equality under the Constitution.

“This lawsuit was led by the feelings of people struggling for a few decades for being forced to change their original names piling up,” Aono said. “For the lawsuit, there has been also a big impact on the Internet. I want to expand the momentum to form public opinions.”

The lawsuit, filed by a legally married man to seek the right to choose a legal name option upon marriage, is the first of its kind in Japan, said Tomoshi Sakka, an attorney representing the plaintiffs.

Along with Aono, president of Cybozu Inc., a software company in Tokyo, another plaintiff is a woman who is now in a legal marriage. Both changed their surnames upon marriage. The other two plaintiffs are in a common-law marriage. Other than Aono, the plaintiffs are in their 20s.

According to the suit, the two plaintiffs in legal marriages claimed that they had to pay huge amounts in fees to change the ownership names of their stocks. Also, depending on the occasion, they were forced to use their former names for business purposes.

As for the two other plaintiffs, both the man and woman didn’t want to change their last names because the woman’s maiden name is a very rare one. The couple ended up choosing a common-law marriage, which doesn’t legally require them to change their last names.

In reference to using separate surnames for married couples, the Grand Bench of the Supreme Court ruled in December 2015 that the Civil Law provisions requiring of a common name shared by a husband and wife was deemed constitutional.

The reason given is that the same surname for a married couple is a system established in society, and it is rational to decide on one surname for a family. The ruling passed the discussion along to the Diet, but no progress has been made on the matter.

For the lawsuit filed this time, the four plaintiffs have focused on the Family Register Law, not the Civil Law.

When Japanese and foreigners marry, they can legally choose to use the same or different surnames. Japanese couples have no option to choose different ones.

The plaintiffs claimed that the current situation is a violation of the Constitution and casts a question on the nation that has failed to take legislative measures.

“There are people around who have suffered," Sakka said. "By using a different legal argument from the 2015 ruling by the Supreme Court, I want to create a major social movement."