Japanese trust banks acting for pension funds bought a net ¥3.16 trillion in foreign bonds in May, the highest since records began in 2005, laying bare a voracious hunt for yield that transcends rising domestic interest rates. The bulk of the flows, analysts in Tokyo believe, headed into US Treasuries, where benchmark 10-year yields climbed to 4.69% in mid‑May, the highest since January 2025. Viewed from Washington, the Japanese buying spree offers a welcome source of demand for American government debt at a time of fiscal strain. In London, strategists see the purchases as part of a structural shift in the world’s largest pension system, one that promises to shape global bond markets for years.

The outward surge in capital coincided with a hefty current account surplus of ¥3.9 trillion in April, the fifteenth consecutive month in the black, driven by a rebound in goods trade and rising income from overseas subsidiaries. Exports rose nearly 14% on robust semiconductor trade, while imports climbed 9.5%, partly on crude oil. Yet this external strength masks fragility at home. Revised data showed Japan’s economy expanded at an annualised 1.8% in the first quarter, a significant markdown from the preliminary 2.1%, after business investment was slashed to a 0.7% quarterly contraction. The downgrade reflects a pull‑back in capital spending by large corporates, rattled by the escalation of conflict in Iran and a spike in oil prices in early March.

While investment falters, corporate borrowing is accelerating. Total debt among Nikkei 225 companies reached ¥678 trillion, up 4.6% year‑on‑year, as firms raise cash for record merger and acquisition activity and growing shareholder returns. All three major rating agencies recorded more downgrades in 2025, raising concerns about credit profiles in a boardroom culture increasingly geared toward aggressive capital allocation. The shift from the traditional hoarding of cash to a more activist deployment of resources, welcomed by investors in Tokyo and New York, now tests the limits of Japanese balance‑sheet discipline.

Looking ahead, the combination of robust external flows, a large surplus and tepid domestic investment leaves Japan’s recovery on a knife‑edge. The Bank of Japan’s tentative steps toward policy normalisation could alter yield differentials and redirect capital flows, while turmoil in the Middle East threatens to keep input costs elevated. For global investors, Japan presents a dual narrative: a giant offshore creditor whose pension funds increasingly shape foreign bond markets, and a domestic economy still struggling to translate record profits into sustained, broad‑based growth.