Jiji and NHK report the opposition set PM-attended intensive deliberations as the condition for advancing bills, while the premier balked at attending.

Five opposition parties confirmed a blanket refusal of upper-house deliberations, halting Diet business; the lower-house speaker is consulting parties on a way out.

Even within the ruling party there is concern that a hardline course offers no exit, as the legislative calendar tightens.

Witness-summons disputes over campaign-video allegations are entangled too, pointing to a package deal.

Japan's political direction affects ties with Seoul and Beijing and trade policy, so neighbors are watching whether the Diet normalizes this week.