Bank of Japan Gov. Haruhiko Kuroda's stimulus policies are backfiring in the housing market, where mortgage rates are rising even as the central bank floods the financial system with cash.

Fixed 35-year home-loan costs rose to 1.81 percent this month, the first increase since February and up from an all-time low of 1.8 percent in April, according to data compiled by the Japan Housing Finance Agency.

The BOJ's April 4 announcement that it would double bond buying to generate 2 percent inflation unleashed the highest government-debt volatility in a decade and pushed 10-year yields up by five basis points.