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The exposé leaned heavily on documents anyone could request, such as land registries, corporate registrations and political fund reports, which a research team cross-referenced to trace how the same names, addresses and parcels reappeared across supposedly separate entities. These verifiable filings were supplemented by other sourcing, including anonymous company officials explaining political donations.
Tachibana exposed paper companies such as Shinsei Enterprise and Muromachi Industries, tied to Tanaka's circle, that had little real operation but bought and resold land. The layers of nominally separate firms made it harder to see who ultimately profited from the transactions.
Entities linked to Tanaka acquired cheap land, such as riverbed parcels along the Shinano River in Niigata, whose value then rose when government projects like levee construction or development plans made it usable. A politician who shapes where public money goes can position private holdings ahead of those decisions. Public spending becomes a private capital gain.