Originated as a nucellar seedling of Miyagawa Wase, recovered from a controlled pollination experiment involving Poncirus trifoliata at the Okitsu Horticultural Research Station (1940). Although genetically maternal, it differs from Miyagawa through stable physiological mutation, showing earlier maturity, reduced flowering intensity, and improved sugar accumulation. Fruit somewhat more oblate than Miyagawa, but averages higher in sugar content and matures a week or so earlier. Trees also more vigorous.