The 150-day ordinary Diet session that kicked off Monday will be an opportunity for the opposition camp to confront the new Liberal Democratic Party administration of Prime Minister Shinzo Age in the runup to the July Upper House election.

Although still in control of the upper chamber, the opposition camp, particularly the Democratic Party of Japan, which was clobbered in last month's Lower House election, is struggling to stay relevant.

After its landslide win last month, the LDP is bent on regaining a majority in the Upper House, and hence a clear voter mandate for Abe.