The Ezo flying squirrel (Pteromys volans orii) or Ezo-momonga (Japanese: エゾモモンガ) is a subspecies of the Siberian flying squirrel. It is endemic to Hokkaidō, Japan, part of the region once known as Ezo. In the legends of the local Ainu, the Ezo flying squirrel or A-kamui (Ainu: アッ・カムイ) is a tutelary deity of children. Together with the Ezo chipmunk (Eutamias sibiricus lineatus) and (Sciurus vulgaris orientis), it is one of the three sciurids (members of the squirrel family (Sciuridae)) found on the island, to the north of Blakiston's Line, each having its own particular ecological niche.