A senior strategist at Bank of New York Mellon is using the price of a Japanese fast‑food staple to capture the yen’s weakness as the recent intervention fades. Geoff Yu created the Katsu Curry Index as an alternative to The Economist’s Big Mac Index, saying a pork‑and‑rice dish reflects the yen’s retreat better than burgers.

On Wednesday the market showed one dollar buying about 159.23 yen, but Yu’s calculations, based on curry prices, indicate the dollar should buy only 62.18 yen, while the Big Mac Index suggests 80.30 yen. This gap shows the yen is significantly undervalued.

The yen fell to a 15‑year low after the most dramatic intervention in 15 years, then recovered half its gains. A weak yen makes overseas travel and imports costly for Japanese consumers and pushes up domestic prices for meals and services. Yu warns that if katsu curry becomes unaffordable, pressure for policy change will grow.

Other PPP indexes include the Tall Latte Index for Starbucks coffee and the KFC Index for Africa. Yu’s Katsu Curry Index uses prices from Co Co Ichibanya, the world’s largest curry‑rice chain with about 1,500 outlets, highlighting a wide gap that suggests the yen needs to strengthen to match high‑income purchasing power.