Abstract: An information notification device includes a longitudinal-data storage unit that accumulates, for a plurality of samples, longitudinal data indicating a temporal change in foot size of one sample, a user-data storage unit that stores user data containing a gender, an age, and a past foot size of a prediction target person, a foot-size prediction unit that predicts, based on a current foot size of the prediction target person and the longitudinal data, a change in foot size of the prediction target person in a period from a current point in time to a future point in time, and a notification processing unit that displays, on a display unit, the prediction of the change in foot size of the prediction target person in the period from the current point in time to the future point in time.

Abstract: A shoe purchase recommendation device 10A includes a user information acquisition unit that acquires user information including a first foot size that is a foot size of a user, a foot-size prediction unit that predicts, based on the first foot size of the user, a second foot size that is a foot size of the user at a future point of time, a growth-end determination unit that determines, based on the second foot size, whether foot growth of the user has ended at the future point of time, a product information storage unit that stores child product information and adult product information, a product information selection unit that selects, based on a result determined by the growth-end determination unit, product information regarding shoes from one of the child product information and the adult product information, and a display processing unit that displays the product information regarding shoes selected by the product information selection unit on a display unit.

Abstract: A sole includes a buffer member extending along an axis connecting a toe and a heel, the buffer member being twisted around the axis along at least part of the axis.