Traditionally, one succeeded in Japan as a politician by ensuring strength in just three areas: money, connections and popularity. Money, in the form of campaign funds that were returned to supporters via all manner of public works' projects, was — and remains — the most important.

But journalists, scholars and interested members of the public hoping to follow the money trail to its sources have been confronted with daunting amounts of time-consuming paperwork.

Under the Political Funds Control Law, all Diet members must report their sources of income. But the amount of time needed to track down who gave what to whom has been seen as a considerable obstacle.