When the extraordinary Diet session convenes on Friday, 15 government-sponsored bills are expected to be submitted — one of the lowest totals since Prime Minister Shinzo Abe's second stint started — reflecting his administration's determination to focus its energy on revising the Constitution.

But coming to an agreement on a constitutional revision bill that can then be put to a nationwide referendum is likely to prove the most contentious debate, with the opposition parties now either staking out, or reaffirming, their position on the issue.

As it stands, the pro-revision camp does not have the two-thirds majority in the Upper House that would allow the Diet to submit a proposal.