HIBA, Japan -- What Miho Kakuno hated worse than the beatings was the bathtub treatment. It took place once or twice a week, even in winter.

Miho says that she and her younger brother were placed in the tub, while their stepfather filled it with cold water and covered them with a wooden top, leaving only a couple of inches of air for them to breathe. They could never push off the cover, she said, because there was something heavy on top.

Now, several years later, Miho, 12, is one of the lucky ones. Her grandmother eventually won custody of her, and she is living quietly trying to recover her equilibrium. Her brother, Hiroki, now 10, eventually ran away and, like his sister, lives in a location that is being hidden from their parents.

Miho and Hiroki's story of abuse is just one of many that have come to light as Japan begins to confront a problem many Japanese did not believe existed. Japan's unusually strong families are being strained, weakened by the long recession and record unemployment, which have undermined stability in the home. In addition to economic pressures, divorce rates and remarriages are rising, which experts say has led to abusive behavior by some stepparents.

"In pediatric circles we thought there wasn't much child abuse and that we were different from the United States because our culture was different," said Dr. Seiji Sakai, a child psychiatrist and director at the Center for Child Abuse Prevention. "The single biggest problem was society realizing that there is child abuse."

But efforts by doctors, lawyers and welfare workers, as well as a recent campaign by the Mainichi Shimbun, a national newspaper, have begun to raise awareness. Recently, Parliament focused for the first time on the increase in child abuse cases by questioning bureaucrats and ministers. Lawmakers are considering relaxing rigid laws that give considerable power and autonomy to families and parents.

Statistics suggest a rise in child abuse, although experts are uncertain whether more is actually occurring or whether more instances are now being reported.

"Child abuse is on the rise in Japan," said Machiko Ayukyo, a lawyer who handles child abuse cases and is a director of the Center for Child Abuse Prevention. "Superficially, it seems the trend is rising," she said, because more is coming to light. "I feel that this has been happening for a very long time and it is finally just coming to the surface," she continued.

This year, the Ministry of Health and Welfare commissioned its first child abuse survey. It also plans to start specialized training for social workers in child abuse, to provide increased psychological support for abused children and to distribute a video to publicize the problem.

Newspapers are also increasing their coverage of individual cases, like one in which a couple left their 5-month-old infant in a coin locker one night last May, and went to eat at a nearby noodle shop. A passer-by heard the infant's cries and summoned the police.

Traditionally, the police rarely investigated accusations of child abuse or wife beating, believing these were issues best left to the head of the household -- meaning the father or grandfather. Authorities are now struggling to figure out when and how to intervene.

Government statistics show that in 1997, there were 5,352 reported cases of child abuse, a 30 percent rise from the previous year. But statistics may not present a full picture because the Government has not traditionally kept track of cases and few are reported to authorities.

"These figures are just the tip of the iceberg," said Satoru Saito, director of the Institute of Family Functioning in Tokyo, who said that changes in the family are leading to more child abuse. "The family's relationship with relatives and the community is not so close anymore. Parents rarely seek support outside and they tend to be isolated from society."

Dr. Sakai, the psychiatrist, says that doctors often see injured children but do not investigate enough. A couple once brought in a 5-month-old baby who died from a cerebral hemorrhage -- but even after an autopsy, the death was not attributed to child abuse but rather to sudden infant death syndrome.

He also cannot forget the case of a young girl, now 7, whose parents he described as highly educated and well-to-do. They brought her to the hospital with a bone fracture when she was 6 months old. Then a year later, they brought her in with a cerebral hemorrhage.

Normally, a child would have died from the injury, but this girl lived. Now, protected in a special school for the handicapped, she is paralyzed and mentally retarded.

"I'm shocked that the second time, when the child had a hemorrhage, the doctor didn't report it as child abuse," Dr. Sakai said. "We have tried to ask about what happened and why, but the problem is that the mother doesn't speak up."

For Miho and Hiroki, the two children held down in the bathtub, the problems began when their father died and their mother, Mieko, quickly moved to the distant city of Nagano from Osaka to live with a small-time shop owner who was tall, handsome and charming.

Mieko's mother, Misako Ishibashi, objected to the relationship, partly because the shop owner, Kiichiro Kakuno, was married. But Mieko persisted and eventually married Kakuno, and Mrs. Ishibashi gradually began to wonder what was happening to her grandchildren.

Mieko sometimes visited with her children, and Hiroki once came with a big bruise on his head and what looked like a small burn on his back. Mieko said that Hiroki had stumbled on the street. When it was time to climb into the car to return to Nagano, he wailed.

Then one day in 1992, Mrs. Ishibashi received a call from Miho's nursery school teacher. Could she please come to Nagano to see what was happening?

When she arrived, she was shown two large volumes of photographs that the teachers had taken of her grandchildren, both with bandages, bruises and cuts all over their bodies. In one picture, Hiroki's face was so black and blue that it was swollen like the moon, Mrs. Ishibashi said.

"We were overwhelmed," she recalled.

They waited until Mieko came to pick up Miho and took her to a nearby restaurant to ask her about the children. Mieko dodged their questions, repeatedly changed the subject and then left.

The Kakunos could not be reached for comment. They have no lawyer, and no listed phone number in the Tokyo area. They have refused to accept court documents and have not appeared in court. Two years ago, Kakuno denied all accusations of child abuse in questioning by a lawyer. Asked about the bathtub treatments, he told the lawyer that he was teaching his stepdaughter Miho how to swim, court documents say, and he said he never tortured her.

The children's grandparents went to the local police, who told them that unless they could prove how the injuries occurred, the police could do nothing. Moreover, if Mrs. Ishibashi were to take the children away, she would be arrested for kidnapping. When she called the local child consultation center, which has the power to shelter an abused child, she was told that even suing in the courts would be very difficult.

Japan has tried to keep its family structure relatively intact with laws that give enormous authority to the family. The tradeoff has been that abused children are sometimes trapped with abusive parents because authorities do not want to interfere.

For centuries, Japanese believed that children were like possessions and that parental authority was virtually supreme.

"In Japan, the right of the family head was very strong," said Toru Arichi, a professor of family law at Kyushu University. Until the 1860's, he said, "When a father unintentionally killed a child, by being too strict or too violent, he was not questioned."

ven now, authorities do not know how to handle mistreatment by parents. On May 15, a 23-month-old girl was brought unconscious to a hospital, where she was pronounced dead. She was only 11 pounds, less than half the average weight of a typical 2-year-old.

Her mother, who was 18, was arrested after admitting that she had not fed her baby much that month and had given her nothing during the previous few days. The mother had separated from her husband after giving birth, and had a nighttime job, but simply had lost interest in caring for the child.

After deliberating a court sent the mother to a juvenile home for a few weeks of evaluation.

Even when authorities are aware of mistreatment, it often takes years before the children can be rescued because of rigid laws that protect the right of parents. In the case of Miho and Hiroki, it took about nine years for their grandmother to win custody of both of them.

Rigid laws coupled with a cultural deference to the parents prolonged the agony for Miho and Hiroki, even though neighbors repeatedly reported evidence of abuse to authorities.

"I hated everything," said Miho, who seems shy and hesitant throughout a long interview.

The first time she ran away, with the help of a teacher, school director and a police official, she was kept for a few days at the local child consultation center. But she was returned home when her mother and stepfather demanded her back.

In 1994, the family moved to Tokyo, and after Miho began playing with a friend downstairs she ran away to her friend's family, who reported the problem to the local authorities. But she went back home soon after because the authorities declined to help her. When she tried to escape again, the child center recommended that she not be returned home. But since it had no legal authority to keep her, Kakuno was able to collect the child.

Then, after months of silence, a neighbor reported to a child center that Hiroki had been found one morning wandering near a large train station in muddy pajamas. Miho secretly had helped her brother escape.

The child consultation center ultimately protected Hiroki and called a lawyer who helped Mrs. Ishibashi sue her daughter for custody.

A year after Hiroki left, Miho escaped. She had spent many hours plotting. She had been to school, where she told her teachers about her plan, and then she went to a friend's house. She prepared clothes and a small bag and left it with them.

She had once tried to leave by the front door, but had been caught. This time, she tried the window from her third-floor room. She piled up furniture in front of the window to climb out. She climbed sideways on the veranda to get to a hallway window, which she entered to go down the stairs. She took her in-line skates with her so that she could make a swift getaway over the hills

As she recalls the whole period of mistreatment, Miho gets a faraway look in her eyes, and it is clear that it still haunts her.

"When I first got here, I was a little worried," she said. "I worried about whether I can belong here, about whether I can survive here, and about what I should do if Dad or Mom and those kinds of people come here to get me."