The Bank of Japan at desk depth — because the yen is the world's carry-trade funding currency. Decades of zero-rate policy made borrowing yen nearly free; that cheap yen funds long positions across global risk assets. This engine fuses the BOJ balance sheet, the post-NIRP rate path, the 10Y JGB, the US-JP differential and USD/JPY into one yen-carry-unwind risk score. The August 2024 unwind is the reference event.