Japanese police have built up an enviable record of solving a higher percentage of crimes than their colleagues in other industrialized countries.
The high incidence of catching criminals, in fact, is considered an important factor in keeping the overall crime rate far lower than in the United States and Western Europe. Japanese police enjoy this success, to a large degree, because of cooperation from public trust in police incorruptibility.
That image, however, has been tarnished in recent weeks.
In the commercial capital of Osaka, nine policemen are under arrest for allegedly accepting bribes from illegal gambling operations for tip-offs about forthcoming police raids. The scandal has led to the suicide of two police officers.
Meanwhile, in Gumma prefecture, north of Tokyo, a man sought for sexual offenses against women turned out to be a young policeman, reviving public memories of a similar recent incident in Tokyo. The two incidents have been headline news because, first, police scandals are not that common but, second, they seem to be on the increase.
Commented one leading newspaper: ''Japanese police enjoy a high reputation here and overseas. People here, for example, have almost taken it for granted that when a drunken driver is stopped and offers a policeman a bribe he is instantly arrested. Now we are not so sure.''
There have been five major cases of police corruption reported in the past six years, mostly involving bribes to high-placed officers for turning a blind eye to violations of the law or for tip-offs to underworld gangs. All have occurred in western Japan centered on Osaka.
This has led to widespread speculation that there is an ''endemic'' factor in the mental framework of Osaka people, traditionally devoted to making money, that makes police (and government officials as well) particularly vulnerable to temptation.
The Osaka region, where the country's major gangs are mostly headquartered, in fact, often looks like a pale imitation of Chicago in the 1920s and 1930s.
Slot machines, like those in American casinos, have become a lucrative source of gang income. Such gambling, however, is illegal in Japan, and game centers with slot machines have to have them modified so that a certain amount of skill is involved - not just sheer chance - and winnings are kept to within $10 worth of soap, candies, etc.
Police have been conducting frequent raids on game centers suspected of evading this restriction. The latest scandal in Osaka surfaced when a retired police sergeant working for a gambling machine leasing company was arrested for using his old contacts to obtain tip-offs about the raids. Nine policemen have been arrested so far - a tenth policeman under suspicion committed suicide proclaiming his innocence - and prosecutors have said more arrests may follow.
The case became a national cause celebre, however, when the former boss of the arrested policeman, Tadashi Sugiura, recently appointed president of the National Police Academy, hanged himself to accept ''responsibility'' for the damage to the police image. Mr. Sugiura, who had also been a former chief of police for the Osaka area, left a note saying ''I feel acutely the responsibility for the affair involving some of my men during my tenure as head of the (Osaka) prefectural police.'' .
Many thoughtful Japanese accept that police have human weaknesses, like themselves, and cannot be expected to be paragons of virtue in every case.
But at the same time, public confidence in their police force is considered vital to the fight against crime. A government poll last year found, for example , that 51 percent of those surveyed would volunteer information to police because of this trust.
A spokesman for the National Police Agency commented: ''Obviously these incidents have shaken public trust and we have to be deeply concerned. Studies are underway on tightening internal discipline and improving the education of young policeman. But although we can monitor their lives to some extent, there are obvious limitations in a democracy.''