Type of winter squash, a Japanese variety of the species "Cucurbita maxima". In Japan, "kabocha" may refer to either this squash or to the western pumpkin.
Kabocha is hard on the outside with knobbly-looking skin. It is shaped like a squat pumpkin and has-green skin with a vibrant yellow/orange flesh. In many respects it is similar to buttercup squash but without the characteristic protruding "cup" on the bottom end. An average kabocha weighs 2-3 pounds.
It has a strong yet sweet flavor, sweeter than butternuts and moist, fluffy texture like chestnuts. It is similar in texture and flavor to a pumpkin and sweet potato combined. The rind is edible although often peeled. It is rich in beta carotene, iron, vitamin C, potassium, and smaller traces of calcium, folic acid, and B vitamins.
When kabocha is picked it is still growing, so unlike other fruits & vegetables, freshness is not as essential. It should be fully matured first, to maximize flavor, by first ripening the kabocha in a warm place for 13 days to convert some of the starch to sugar. Then it is transferred to a cool place and stored for about a month in order to increase carbohydrate content. Fully ripened kabocha will have reddish-yellow flesh, hard skin, and a dry, corky stem. It reaches the peak of ripeness about 1.5–3 months after harvesting