Tokyo (CNN) -- Parents torn apart from their children protested in Tokyo on Sunday, calling on the Japanese government to sign an international treaty that would reunite them with their sons and daughters.
"Stop parental child abduction," the parents cried. "Sign the Hague Convention."
The Hague Convention on the Civil Aspects of International Abduction is a multilateral treaty that dates to 1983. It often comes into play when parents divorce, and one parent takes the child back to his or her home country, keeping the child away from the other parent who may have partial or full custody. The treaty effectively forces signatory nations to recognize that custody.
Dozens of countries have signed onto it -- the official website lists 84 "contracting states" to the convention -- but Japan is not among them.
Calls for Japan to sign the convention have increased as heartbreaking stories have come to light.
U.S. Secretary of State Hillary Clinton addressed the issue after a meeting this month with Japanese Minister of Foreign Affairs Seiji Maehara.
Clinton said she had "encouraged Minister Maehara and the Government of Japan to work toward ratification of the Hague Convention on the Civil Aspects of International Child Abduction."
Among those protesting Sunday was Masako Akeo Suzuki, who had married a Japanese man in Vancouver, Canada. After their divorce, her ex-husband returned to Japan with their son without notifying her. He then got sole custody in Japan, and kept the child from her.
She doesn't even know where in Japan her son lives.
"I love him like all parents do, I miss him very much" she said in tears. "I want to hold my son. Please help me and my son. Please help me. ... Kids are suffering."
Suzuki helped organize Sunday's event. "I sometimes lose my patience and almost give up my hope," she said, adding that she "can't stop" for the sake of her son "and other children."
Japan is the only G7 country not to sign the convention.
Yomiuri newspaper, one of Japan's biggest papers, reported that the country has decided to set up a council to weigh joining the convention. The council would compile a report by the end of March that could allow Prime Minister Naoto Kan to make an announcement on joining the convention during his scheduled visit to the United States in the spring.
Kevin Brown, a father who could lose all rights to see his son, told CNN it's time for Japan to sign.
"They've been saying the same thing for 20 years: 'We are studying this issue, we are thinking about it doing it.' But they never make any changes. It's time -- they need to make the change."
But some critics say Japan joining the convention would not solve cases of international parental abductions. They argue Japan's domestic legal system needs to be improved and prepared for the increasing numbers of marriages between Japanese people and foreign nationals.
CNN's Junko Ogura contributed to this report.