It is a mouse about the size of a medium-sized dog and is said to eat even a cat; on the other hand, sometimes it is said to mate with a cat and rear its blood-related kittens (as later described).
中型イヌほどの大きさで、ネコすらも食べるといわれる鼠であるが、その反面、猫と交わり、血のつながった子猫（後述）を育てることもあるという。