Days later, Japan's benchmark yield hit a 30-year high above the key 3% milestone, piling pressure on Takaichi to water down her spending ambitions.
"Given Japan's huge public debt, Japan needs to present a credible medium- to long-term fiscal outlook, and demonstrate consistency between monetary and fiscal policy, to avoid an unwelcome spike in long-term interest rates," said Mitsuhiro Furusawa, Japan's former top currency diplomat.
U.S. scrutiny of Japan's finances prompted Katayama to assure her G20 counterparts that Japan would shed its over-reliance on additional spending and avoid issuing debt to fund tax cuts.
In comments to reporters after a meeting with Bessent at the G20, Katayama recounted showing him remarks by Takaichi to Japanese newspaper Yomiuri that stressed the premier's resolve to "achieve growth and fiscal discipline simultaneously".
"He seemed to understand, saying that's very good," Katayama said.
A week later, Bessent was again helping Japan with strong warnings against yen bears, saying he had asymmetric information and good insight into what Japanese policymakers, including the BOJ, would do.
"I am the house now," Bessent said this month, adding "you can bet against me if you want."
The yen jumped against the dollar.
Bessent's demands broadly align with the policy direction of the BOJ, which is expected to lift rates again on Friday.
On fiscal plans, there's a bigger gap.
Takaichi cannot easily retreat from flagship stimulus plans that drove her party to victory in this year's election. Her handouts and subsidies to curb fuel costs also helped ease anger over rising cost of living.
Forcing Takaichi to abandon tax plans is also risky for Washington if it weakens an administration of a reliable U.S. ally to counter an assertive China. After joining Tokyo in shoring up the yen, President Donald Trump emphasised the importance of the U.S. partnership with Japan.
In a move that analysts saw as placating markets and Bessent, Takaichi reappointed Katayama as finance minister in a cabinet reshuffle on Thursday.
Katayama - a fiscal conservative at heart - has walked that line since taking office, reassuring markets Japan won't spend recklessly, even as she promotes her boss's investment ambitions.
For now, there are no signs Takaichi is backing down. Budget requests for the next fiscal year have ballooned to 143 trillion yen ($916.14 billion), near pandemic-era levels.
Takaichi has pledged to keep new bond issuance at around 40 trillion yen for the fiscal year ending March 2028, above this year's projected 32.7 trillion yen.
Some officials say that goal could be hard to meet given the temporary sales tax cut, increased defence spending and rising financing costs.
So far, the fiscal standoff is contained — a sign of how much diplomatic capital Takaichi still has with Trump.
Some analysts, however, say Bessent's approach to Japan over its finances represents an extension of Trump's trade playbook.
The Asia Group's Boling said the Trump administration has "never been bashful" dealing with allies, as seen in trade negotiations.
"I think we're seeing that now more for financial policy matters," he said.
($1 = 156.0900 yen)