The relationship between US 10-year Treasury yields and 10-year Japanese Government Bond yields, which historically moved together (shrinking spread = yen strength), broke in late 2023-early 2024 when the spread compressed but the yen weakened instead of strengthening, signaling that markets have begun pricing in that Japanese debt saturation is near and will force either yield curve control (money printing) or bond market collapse, marking the beginning of the acute stage of the debt crisis.