The Polish pavilion.Photo: Danuta Isler/Radio Poland
Over 170 countries are participating in the event - which is hosted by Japan for the third time - with Russia not invited to participate and Ukraine's presence supported financially by the organizers.
Danuta Isler is in Osaka and filed this report a day after the Japanese media toured the site and a day before the Japanese Emperor will be the Guest of Honor.
Click on the audio player above to listen to the report.