Japan’s 4% bond yield spike threatens the low-cost borrowing strategy behind corporate Bitcoin buying

- Japan's 30-year just printed 4.079% — the highest since 1999 — and Metaplanet's cheap-yen Bitcoin flywheel just hit its first real funding wall. The company's existing ¥8 billion zero-coupon bond and first BitBond tranches are locked, but every future issuance now has to clear a materially higher hurdle. The math that made this look like genius — borrow near-zero yen, buy BTC — only worked while the Bank of Japan kept rates pinned. That era is over. Higher Japanese yields don't break the existing stack; they just make the next round of corporate-Bitcoin borrowing measurably more expensive, which is exactly when leverage addicts discover the difference between a trade and a thesis. Someone didn't read the manifest.