A Japanese court rejected Monday a damages suit filed against the state by a business executive and three others who argued that the Japanese legal requirement for Japanese married couples to use the same surname is unconstitutional.

The Tokyo District Court ruled the Japanese family register law, which does not allow spouses to use different surnames, is constitutional, saying there is "a reasonable ground."

Under the current system, spouses can choose whether to use the same surname when a marriage takes place between a Japanese and foreign national. Divorcees can also choose whether to continue using the same surname regardless of nationality.

The plaintiffs -- Yoshihisa Aono, the 47-year-old president of software developer Cybozu Inc., a woman from Kanagawa Prefecture and a common-law couple from Tokyo -- had claimed the law violates the constitutional right to equality and the pursuit of happiness.

But Presiding Judge Tetsuro Nakayoshi said the Civil Code provision stipulating a single surname for a husband and wife is constitutional and it is reasonable for the family register law not to allow separate surnames.

In December 2015, the Supreme Court upheld the constitutionality of the provision, saying the use of a single surname for family members is an established practice in Japanese society. The latest suit focused on the family register law instead.

(Yoshihisa Aono enters the court building on March 25, 2019.)

"The (latest) ruling only echoed the top court's ruling in 2015. We wanted the court to make a decision that takes a step forward," said Tomoshi Sakka, the lawyer representing the plaintiffs, at a press conference following the ruling.

Aono said at the press conference, "I wanted the judicial authorities to say there is something wrong when there has been no progress in the debate (over separate surnames) in the Diet." He also expressed hope for quick legislation to allow Japanese married couples to use separate surnames.

Aono adopted his wife's surname, Nishibata, when they married in 2001, but for business purposes he uses his former surname with which he said he had built trust and status.

He argued he has suffered as a result of being forced to think which surname he should use every time he signs a business contract and having to pay a large sum to alter his registered name for stockholdings after he got married.

Many companies and public offices in Japan now allow employees to use their previous surnames at work. But only registered surnames may be used in principle in official documents such as driver's licenses and passports.

In Japan, it is customary for a wife to take her husband's surname, although the law does not say which of the partners must give up their surname on marriage.

Most countries allow the use of separate surnames by married couples and the U.N. Committee on the Elimination of Discrimination against Women has urged the Japanese government to amend the Civil Code.

Opposition parties have repeatedly submitted bills to amend the Civil Code, but they have been blocked by conservative members of the ruling Liberal Democratic Party.