Japanese sovereign debt markets witnessed significant movements as yields on long-term bonds retreated sharply amid political developments. With the nation's upper house election drawing near, both 30-year and 40-year benchmark government bond yields tumbled by 10 basis points.

The 30-year bond yield settled at 3.06%, marking a notable decline from previous levels. Simultaneously, the 40-year maturity followed suit, sliding to 3.38% as investors repositioned portfolios ahead of the parliamentary vote. This synchronized drop across the yield curve's longest tenures reflects mounting market sensitivity to political transitions, with bond prices climbing inversely to yield movements. Market analysts observed that such pronounced shifts in ultra-long yields typically signal institutional anticipation of policy continuity or economic stability post-election.