Yen hovered around 159.9 per dollar, briefly breaching the 160 level that previously triggered intervention in April.
Tokyo has spent a record 11.7 trillion yen ($73 billion) since April defending the currency, but pressure persists due to US‑Japan rate differentials.
Finance Minister Satsuki Katayama signaled readiness to act, while MUFG analysts expect possible intervention if speculative selling intensifies.
Markets await BOJ Governor Kazuo Ueda’s speech and June policy meeting, expecting another rate hike to curb inflation and support the yen.