The Nut fruit tortrix (Cydia kurokoi) is a moth of the Tortricidae family. It is found in Japan, the Korean Peninsula and eastern China.The wingspan is about 20 mm. Adults are on wing in August and September. There is one generation per year.The larvae feed on Castanea seguinii, Castanea mollitissima, Castanea crenata and Quercus acutissima. The larvae feed inside the fruits of chestnut trees and damage them.