SMBC Nikko Securities senior foreign exchange and rates strategist Rinto Maruyama stated that Japan's suspected currency intervention may have been driven by sharp rises in both Japanese and U.S. long-term and super-long-term government bond yields.

He noted that intervening before the Bank of Japan's policy announcement "may have been intended to catch markets off guard and maximize the impact of the intervention. This contrasts with the more transparent and easily identifiable intervention seen in April."

Recent senior personnel appointments at Japan's Ministry of Finance could help solidify the government's intervention framework and decision-making process.

New intervention is likely only if the yen weakens again following the BOJ's meeting.

"If the market interprets the BOJ's post-meeting statements as dovish, putting upward pressure on USD/JPY again, that could provide an opportunity for authorities to re-enter the market for intervention," Maruyama added.