This is a gooey wild yam from Yamanishi prefecture served over white rice and found at Aoyama vegetable market on weekends. This venodr sells the yams in the winter months and offers a small menu of yams grated over rice. Yamanashi Prefecture is located immediately west of Tokyo in the Chubu region, the northern half of Mount Fuji and the Fuji Five Lake region are located in Yamanashi Prefecture.