Sugar Mountain has the appearance of a young girl, with dark hair in a hime cut and straight, eyebrow-level bangs. She wears a bonnet, a necklace in the shape of a cluster of grapes, a short dark dress with a light one underneath, leopard-patterned sleeves, and long socks with a pair of leather boots.

Behaving much like a young child with a vivid imagination, Sugar Mountain does not seem to have aged physically or mentally during the roughly fifty years she spent bound to the Tree. She passes her time playing make-believe with dolls made from cloth and twigs, and has drawn rooms for an entire 'house' within the tree-hollow she lives in. Johnny deduces that she is nearly blind, noticing the mark of a cane around her abode. In spite of her childish mannerisms, she highly values honesty, and is able to comport herself with some maturity when she explains the Tree and the nature of its Stand to Johnny and Gyro, making sure that they understand that they must use up all of the items given by the spring by sunset. She expresses a strong desire to free her parents and leave the forest with them together, and holds Johnny and Gyro in high regard for their ability to escape the Tree's ability.

At one point in the past, Sugar Mountain and her parents encountered the great tree. Her father had dropped an axe and managed to acquire it back from the guardian, plus a golden axe for being honest. However, Sugar Mountain's family failed in using it up before sunset and they were turned into tree fruits, slumbering for so many years Sugar Mountain lost count of the time. It is estimated that she was prisoner of the tree for about 50 years. At one point, it is Sugar Mountain's turn to be the guardian of the tree.