Iyogin Holdings started testing the $7 trillion market in April with small purchases of superlong bonds, according to its CEO.
The bonds are usually major investment targets to match insurers' long-term liabilities, but expectations yields will rise further amid government spending have slowed buying.
A bond slump that sent yields soaring to records on her election pitch to cut taxes on food has rippled through markets in Tokyo.
The asset manager was previously one of the biggest bulls on Japanese government debt.
For 2026, the only certainty is that this year of the Fire Horse will be shaped both by existing trends that evolve and genuine surprises.
The swap market is now pricing in about a 76% chance of a rate hike when the central bank delivers its next policy decision on Dec. 19.
Bank of Yokohama is prepared to pile back into the domestic debt market when the central bank’s peak interest rate is in sight.