The Bank of Japan is widely expected to kick off a fresh round of rate increases at its September policy meeting, with another adjustment potentially arriving as early as January 2027. Former central bank board member Seiji Adachi has indicated that market expectations have already priced in the move, and any delay could reignite yen weakness while amplifying inflationary pressures from higher import costs.

Trading data as of Monday afternoon in Tokyo suggests roughly an 80% probability that the BOJ will lift rates at its September 18 gathering. Adachi, speaking in an interview, noted that the central bank is under intense pressure to act, given how thoroughly the market has already priced in a hike. "The Bank of Japan has almost been backed into a corner. If it fails to raise rates, the yen could weaken sharply once again," he warned.

During Asian trading on Tuesday, the dollar-yen pair hovered near the 159 level, not far from the psychologically significant 160 threshold. Despite coordinated intervention efforts by both Washington and Tokyo earlier, the yen's softness has not been fully resolved. The central bank now faces a delicate balancing act: keeping rates too low risks intensifying currency pressure, while hiking too aggressively could weigh on economic growth.

Japan has long maintained an ultra-loose monetary stance before exiting negative interest rates in 2024, gradually normalizing policy since then. With wages climbing, inflation holding near target levels, and a weaker yen lifting import expenses, expectations for further BOJ action have been steadily building.

Inflation-driven rate cycle may stretch longer, pushing rates beyond market forecasts

Adachi believes the current inflation environment in Japan is robust enough to support continued rate increases. He anticipates that following a September hike, the BOJ could wait until January 2027 for its next move rather than December of this year, as a second increase within such a short window might appear overly aggressive.

While markets had previously pegged the terminal rate of this tightening cycle at roughly 1.25% to 1.5%, Adachi argues the cycle could persist for a longer period, with the final rate potentially exceeding that band. Overnight index swap pricing reflects a similar view, with markets expecting rates to hit 1.25% in September and rise another 25 basis points by January 2027.

Using a simplified Taylor rule calculation, Adachi suggests the policy rate might theoretically need to climb to around 2.75%. However, he clarifies this is a theoretical exercise rather than a BOJ target. Under such conditions, he projects the policy rate could reach 2% or slightly higher by the end of 2027, above the 1.5% median forecast in a Bloomberg survey of economists.

Yen pressure and US signals push BOJ toward action

Adachi points to recent comments from US Treasury Secretary Bessent as creating a more favorable backdrop for BOJ Governor Kazuo Ueda to proceed with hikes. Bessent has indicated that Japan needs to follow through with policy measures after the coordinated forex intervention, expressing hope that Ueda would push rates upward. This stance, according to Adachi, weakens any domestic opposition to monetary tightening.

"Bessent has repeatedly said the BOJ will be the next central bank to act. In such a situation, the Japanese government cannot tell the BOJ to 'stop,'" Adachi explained. There had been concerns that the administration of Prime Minister Takayuki Suga, which favors economic stimulus, might resist policy tightening. But Adachi believes that with persistent yen weakness and inflationary pressures, it becomes harder for the government to openly oppose rate adjustments.

He suggests that the easiest way for the BOJ to minimize political friction is to let the market form rate-hike expectations in advance, then gradually release policy signals to pave the way for actual action.

Weak consumption emerges as the BOJ's biggest constraint

Inflationary pressures in Japan are clearly intensifying. Government data shows core inflation rose to 1.8% in July, accelerating for a second consecutive month. Given Japan's heavy reliance on imported energy and food, many private-sector economists believe cost increases stemming from Middle East conflicts are gradually filtering through to domestic prices. Adachi projects inflation could potentially exceed 2.5%.

Despite the supportive inflation backdrop, domestic demand remains fragile, presenting a key risk for the central bank. Government figures reveal that personal consumption contracted 0.1% year-on-year in the second quarter of 2026. While some demand was driven by pre-regulatory purchases of air conditioners, overall spending lacks momentum.

"Consumer spending has no driving force. The key question is whether the BOJ can maintain aggressive rate hikes if higher inflation and higher rates continue to weigh on consumption," Adachi said. This means the central bank's future policy path will face dual pressures: yen depreciation and rising import costs argue for continued tightening, while weak consumption constrains the pace of any further increases.