Japan has a long history of xenophobia and dissimulated racism. Rare are violent acts of racism, but numerous are the Japanese who harbour prejudice or fears of foreigners. It is therefore no wonder than the nationalist and openly xenophobe Shintaro Ishihara has been elected and recently re-elected as governnor of Tokyo, where nearly 10% of the Japanese live.

The problem is that Japanese authorities claim that the number of crimes committed by foreigners is rising.

The Japan Times explains the situation :

But what of the data on foreign crime?

The National Police Agency had its most recent White Paper on foreign crime available for download from its Web site ( www.npa.go.jp) conveniently in time for the new Koizumi Cabinet. One look indicates that, yes, after a dip in 2000 and 2001, both the number of foreign crimes and foreign perpetrators have increased.

What is still left out:

The number of registered foreigners in Japan is also increasing year on year: From 1,778,462 in the beginning of 2002 to 1,851,758 souls by the end ( www.moj.go.jp). More people means more potential criminals. So statistics detailing only foreign crime rates both in raw numbers and in percentages only tells half the story.
Indeed, an careful analysis reveals that, whereas the total number of "heinous crimes" augmented, the number of murder committed by foreigners is actually decreasing by 30% between 1993 and 1999, increasing the share of crimes committed by Japanese (what the authorities are not willing to admit). The number of crimes also does not equal to the number of criminals, so that if a single person commits 50 thefts, that will account for 50 crimes.

Here is a very enlightening article from the New Obrserver in 2001

Ishihara's main claim is that crime, and particularly violent crime, is increasing among foreigners. It is true that the number of criminal offenses committed by foreigners has increased, from 12,771 in 1993 to 25,135 in 1999. It is important to note, however, that these are not convictions, but merely arrests, meaning that foreigners were arrested for committing this number of crimes. However, the number of foreigners arrested for criminal offenses actually dropped in the same period, from 7,276 to 5,963. If you calculate the "share" of foreign crime in Japan, the figure rose from 1.8% to 3.4% in terms of offenses, but fell from 2.4% to 1.9% in terms of the number of arrestees.

Naturally, the NPA has chosen to focus on the first figure, the number of offenses, to give the impression of "rising foreign crime" But looking at the number of people arrested, one would come to the opposite conclusion. How does one explain this paradox?

The reason, simply stated, is that there has been an increase in the number of thefts in comparison with other crimes. Typically, a murderer will be charged with one crime. By contrast, thieves are often charged with dozens of crimes after confessing. In one real-life instance, for example, a group of 17 Vietnamese were arrested, and charged with a total of 270 cases of motorcycle theft. This works out to about 15 charges per arrestee. Naturally, it pushes the figure for offenses up, even when the number of people arrested drops. But clearly, it does not mean that Japan is under siege from "foreign criminals".

The situation for "heinous crimes" (meaning murder, rape, arson and robbery) has also been used to demonstrate the danger of foreigners. But here again the statistics are misleading. The number of foreigners arrested rose from 246 in 1993 to 347 in 1999, a rise of 50% or so, so it seems on the surface that foreigners are becoming increasingly dangerous.
Second, if we look at the causes behind this increase in "heinous crime" by foreigners, it turns out that the rise is entirely due to robberies, which rose from 142 to 278. By contrast, the number of murderers fell from 72 to 50.
One of the main issue is that the Japanese authorities and media do not make any distinction between the country of origin of foreigners, and going as far as assimilating illegal residents with all other kinds of foreigners, including permanent residents or investors giving jobs to Japanese.

In my opinion, the clear separation should be made between economic immigrants from developing countries (more likely to commit robberies or thefts) and others, then between each country or at least regions (Europe, North America, South America, SE Asia...), then by visa groups, especially for overstayers.