Chocolate fans in Japan, among Asia’s biggest cocoa buyers, are heading for a sticker shock later this year as an unprecedented surge in cocoa prices finally filters through to stores.

Itochu, one of the country’s top trading companies and cocoa importers, says a sudden spike in the retail price of chocolate is inevitable and expects processors to use more substitutes to rein in costs.

Cocoa prices have been on a tear, with New York futures more than doubling since the start of the year. The rally may have further to run as crop declines in Ivory Coast and Ghana, the top suppliers, leave buyers struggling for beans and traders pulling out of the market make prices more vulnerable to large swings.