In both countries politicians have been receiving large bribes from industry for decades, as they presided over a nationwide patronage system that enriched them and their associates. Organised crime has strong, if murky, links with officialdom.
In both countries the same group of politicians have monopolised power almost since the war - in Italy, the Christian Democrats and the Socialists in a series of coalitions, in Japan, factions of the Liberal Democratic Party (LDP). And the systems have persevered because the alternatives - the Communists in Italy, the Socialists in Japan - were not acceptable to the general public.
In Italy all this has begun to unravel - the left-wing bogey has evaporated with the end of the Cold War, and Antonio Di Pietro, the magistrate from Milan who has been leading the investigations, has proved indefatigable.
In Japan, the old system continues. Although prosecutors found 7,000m yen ( pounds 40.5m) in undeclared gold bars, bank debentures and cash in Mr Kanemaru's office, there has been no move to find out where the money came from, as if it just materialised. Mr Kanemaru will be punished, but the businesses that contributed the money will be let off.
On Thursday the chairman of the Japan Chamber of Commerce and Industry, Rokuro Ishikawa, even had the temerity to speak out against a proposal to ban companies from making donations to individual politicians.
And since it has been revealed that some opposition politicians also received money from the Sagawa trucking company that is linked with Mr Kanemaru, the opposition as a whole has abandoned any attempt to ask awkward questions about the wider ramifications of the scandal.
Everyone is compromised: even the public prosecutors are widely regarded as working under the thumb of the LDP.
Nor is there the same level of public protest in Japan as there is in Italy. Despite the tones of indignation in newspaper editorials ('We have ended up as an economic superpower governed by venal pygmies' said the Japan Times yesterday), it is simply not true that the Japanese public wants to get rid of its corrupt politicians. A poll this week indicated 91 per cent of respondents did not think politicians were trustworthy, but there are no large rallies, no protest lists of signatures, no massive defections from the LDP at elections.
'In Italy the scandal has been exposed in the press,' said Tetsuroh Murobushi, an author of several books on Japanese politics. 'But in Japan, despite the fact that politicians are rotten, the bureaucrats have firm control and the economy is quite strong, so it is easier to conceal a scandal.'
In fact, Mr Kanemaru appears to be the victim of an inter-faction plot within the LDP to break up the formerly powerful Takeshita faction, which used to run the ruling party. Mr Kanemaru and his protege, Ichiro Ozawa, had seemed to many LDP members in other factions to have become too powerful.
According to this theory, enough information was leaked to prosecutors to damn Mr Kanema ru and to neutralise Mr Ozawa, who earlier this year attempted to set up his own faction. But at the same time the prosecutors are being kept on a short leash to stop the scandal spreading too far into the LDP.
It is widely suspected that many LDP leaders were involved in the scandal that felled Mr Kanemaru. But for the sake of stability, particularly in the current economic recession, the national consensus is: don't rock the boat.