I first soaked the chestnuts (15 or so, upper left in the image below) in water for several hours to make it easier to peel the outer hard skin. You could also parboil to make it easier to remove the skin. It is easy to take off the hard skin called "onikawa" 鬼皮 by cutting off the bottom and peeling off the hard skin but the chestnuts are still covered with the bitter-tasting inner skin (upper right). The most labor intensive part is removing the inner skin called "shibukawa" 渋皮 meaning "bitter skin". I just used a small paring knife to remove the inner skin but it is not easy. I put these cleaned chestnuts into water to prevent discoloration (lower left).
P.S. After I posted this, an interesting article appeared in Washington post regrading chestnuts including different types and origins of the chestnuts imported here.