Prime Minister Naoto Kan invited the opposition camp Monday to join a debate on social welfare and tax reforms as the 150-day Diet session opened, saying it is the responsibility of every lawmaker to address these pressing issues.

Kan's humble 19-page policy speech was an overture to the opposition camp to join the deliberations, reflecting his lack of options in dealing with a Diet whose Upper House is opposition-controlled.

Kan, the Democratic Party of Japan's president, cited proposals by the Liberal Democratic Party and New Komeito, the top opposition parties, to set up a common forum for discussing the critical reforms.