Japan's 40-year government bond yield just hit 4%, marking a milestone since the bond's introduction back in 2007. More significantly, this is the first time any maturity of Japanese sovereign debt has reached this level in over 30 years. This shift carries important implications for global risk sentiment and capital flows. When sovereign debt yields spike like this, investors typically reassess their exposure to riskier assets—including crypto markets. The move reflects changing monetary conditions and could influence how institutional capital rotates across different asset classes, from equities to digital assets.