Japanese government bond (JGB) yields rose on Wednesday, with longer-dated yields hovering near one-month highs, as a weaker yen and fiscal expansion risks weighed on sentiment.Here are a few details:The benchmark 10-year JGB yield rose 3.5 basis points (bps) to 2.715%, the highest since June 9. Yields move inversely to bond prices.The 20-year JGB ‌yield was ⁠up 1.5 ⁠bps at 3.670% after touching 3.675%, its highest since late May. The 30-year yield climbed 0.5 bp to 3.950%.The yield on the 40-year JGB, Japan's longest tenor, fell 1 bp to 3.795%.Japanese bond yields rise on yen weakness, fiscal worriesJapanese government bond yields climbed Wednesday, with longer-term rates nearing a month's peak. A weakening yen and concerns over government spending are impacting market sentiment. While the Bank of Japan's stance suggests stable long-term rates, uncertainty surrounding a potential supplementary budget introduces near-term upward pressure on yields. Higher U.S. Treasury yields also contribute to this trend.The yen slid to its weakest level against the dollar since 1986 overnight, touching 162.59 and fuelling speculation that Tokyo could be nearing direct intervention.Prime Minister Sanae ⁠Takaichi's first ‌economic blueprint released on Tuesday called on the Bank of Japan to align monetary policy with government efforts to boost growth, signalling ⁠the administration's preference for low interest rates.Policies under the Takaichi administration are not expected to push long-term interest rates higher over the medium to long term, Noriatsu Tanji, chief bond strategist at Mizuho Securities, said in a note.However, he said uncertainty over whether a supplementary budget will be enacted is likely to linger until autumn, leaving a relatively high near-term risk that yields will move higher.U.S. Treasury yields ticked up overnight, following a better-than-expected job openings report. It is the first in a string of reports on the labour market this ⁠week, culminating with Thursday's government payrolls report."Higher U.S. yields yesterday are also likely to weigh on JGBs, suggesting investors should be mindful of the possibility that long-end yields will keep rising in the near term," Tanji said.Big Japanese manufacturers' sentiment improved in the three months to June to levels unseen since 2018, the Bank of Japan's Tankan survey showed, a sign that the economy was weathering the energy shock from the Middle East conflict for now.