The 12-year-old Tokyo boy had asked his mother to buy him a radio with cassette recorder. She refused, suggesting that he wait until his father returned from a business trip. "You don't care if I die," he replied.

Two hours later, the boy hanged himself with an electric cord from the family's laundry pole.

In another section of Tokyo, a young girl killed herself by leaping from the roof of a 13-floor apartment building. Later, two other girls flung themselves from the same roof.

These and similar youthful tragedies in recent months have sent a shock wave through Japanese society, alarming parents, police and school officials. In one period of 10 days, 11 children committed suicide, provoking a painful national introspection about the pressures facing Japanese youths.

Rummaging through international statistics on suicide, researchers came up with two unsettling conclusions:

The suicide rate among young people Japan is far higher than in the United States or other Western countries. For persons in the late teens and early twenties Japan's rate is twice as high as France's and four times that of Britain's.

Most alarming, the rate has risen swiftly among Japan's younger children. By June of this year, 46 suicides had been counted among youths 10 to 14 - a number equal to the total for that age group in all of 1965. "We face the danger that this is going to increase even more," said a specialist with Japan's national police agency.

Heavy school pressures are frequently blamed for the high suicide rate. Exams which determine a student's entrance to prestigious high schools and colleges are increasingly criticized by just about everyone in Japan as presenting too great a crisis at too young an age. The typical child from an upwardly mobile family spends many extra hours every week in the preparatory schools, or Juku, getting ready for the exams which can determine his future.

Police acknowledge school pressures to be a factor. A 13-year-old boy from southern Japan hanged himself after being struck by an angry teacher and one of the Tokyo girls who plunged to her death this fall left behind a pile of unfinished homework. But in a detailed examination of 398 child suicide cases this year police concluded school pressures were responsible for only about one-fourth.

In fact, police have decided that school pressures are only one of many "triggers" that lead to suicide. School in not so great an ordeal for children 10 to 14, the age group where the most recent increases have been noted. Police and a number of academic authorities argue that soical changes in the Japanese family and the way children are raised have produced the new waves of suicide among the very young.

"Many psychologists and doctors tell us that the children of the present day have no endurance," said one police official charged with investigating the cases. "They do not know how to bear things that are unpleasant to them."

The experts's view is of the "spoiled" child of affluence, accustomed to having what he wants and to having his problems solved by teachers and parents. The child cannot cope with denial, even for a short time - Hence, the young boy who hanged himself when refused the radio.

"They are so very, very fragile," says social psychologist Sumiko Iwao, a professor at Keio University. "They are so spoiled and they are not able to endure pressure - they cannot endure for even the very short period of time needed to find a solution to a minor problem."

Another theory is that modern Japanese children, unlike their parents, have no personal experience with death. There are no grandparents in their small city homes and apartments and they grow up unfamiliar with the awareness of a dying relative. Death becomes unreal, witnessed only in television drams where their hero is dead one day and alive in some other program the next.

In that context, "suicide" does not really lead to something called "death" but is merely an act of rebellion or an appeal for attention. Since the September scare, a number of parents have been horrified to find their children playing a game called "suicide," using real ropes.

Prof. Iwao's 11-year-old son came home from school where another boy's suicide had been followed by a grave discussion led by the principal. He told his mother he thought the boy had not really intended to take his life. "Don't you see, it was just a mistake," he told her.

Some are tempted to explain the tragedies as somehow reflecting Japanese traditions, one of which glorified the act of suicide as the ultimate in bravery and loyalty.In one of Japan's greatest historical tales, "The story of the 47 Ronin," Samurai warriors commit hara-kiri in honor of their lord whose death they had avenged.

Iwao disagrees with this interpretation. Modern times, not ancient tradition, she says, are the reason for child suicides today. "It is hard for me to imagine a 10-year-old sitting around reading "The Story of the 47 Ronin," she says.