According to Wong, with the exception of one long weekend in September 2007 when he took his daughter to Tokyo Disney, her grandparents were present every time he was with Kaya.
He said that a Japanese court investigator found that the girl was washed and inspected every day after a swimming lesson at her nursery school and her teachers never noticed signs of abuse.
ABCNEWS.com was unable to contact the grandparents Satoru and Sumiko Yokoyama, both in their 70s. State Department officials would not comment on the specifics of this case, but a spokesperson said that allegations of abuse were not uncommon in some abduction cases.
Kaya's grandparents are elderly pensioners. Under a Japanese program to stimulate the birth rate, families with young children receive a monthly stipend from the government, one reason Wong believes the grandparents have chosen to keep Kaya.
Though Wong's case is unique in that most child custody disputes result from divorce not death, his is typical of the legal morass in which many left-behind parents find themselves. He has spent thousands of dollars on legal fees and makes regular appearances for court hearings, but his case, like many others, remains stalled.
American parents quickly learn that the Japanese court system is rather different from that of the United States.
There is no discovery phase — pretrial disclosure of evidence — or cross-examination. Lawyers for each side simply present their cases before a judge.
Furthermore, there is no concept of parental abduction or joint custody. The parent or family member who has physical custody of the children — generally the Japanese mother or her family — is granted legal custody.
"Fundamentally, people believe that Japan must have a legal system available to deal with child custody and similar problems," said Jeremy Morley, an international family lawyer. "In reality, however, there is no such system."
"Family law is very weak in Japan. There is also a cultural perception that a Japanese child is best off in Japan with a Japanese parent. Boiled down, the law is: Whoever has possession has possession and the other parent should mind his own business," Morley said.
Culturally, there is no concept of dual custody or visitation. Once a couple gets divorced, the children are typically assigned to one parent and never again have contact with the other parent.
After divorcing his then-pregnant wife of four years in 1982, former Prime Minister Junichiro Koizumi retained custody of his two eldest sons, Kotaro and Shinjiro. His ex-wife Kayoko Miyamoto took custody of their unborn son, Yoshinaga Miyamoto. Since the divorce Miyamoto has not seen her two eldest sons, and Koizumi has never met his youngest son, Yoshinaga.
Against this cultural backdrop, American parents seeking custody find themselves in an endlessly revolving door of hearings that go on for years and yield no results.
Paul Toland, a commander in the U.S. Navy, estimates he has spent "well over $100,000 in attorney's fees" for the last five years in an effort to get back his daughter.
Toland's daughter was taken by his ex-wife to live with her parents in Tokyo while he was stationed in the country in 2003 and he has not seen the girl since.
He began fighting for custody of his daughter Erika, 5, when she was just 9 months old. When his wife, Etsuko Futagi, committed suicide in September 2007, Erika's maternal grandmother took posession.