1. An information processing device comprising: circuitry configured to: store browsing history information of items by a user; store feature amounts information of the items; select a clustering standard, from clustering standards categorizing the items into a plurality of clusters, such that a number of clusters categorized as a known type cluster, in which a probability that an item belonging to the known type cluster is equal to or greater than a first threshold value, is greater than or equal to a first number, the first number being an integer greater than or equal to 1, and such that a number of clusters categorized as an unknown type cluster, in which the probability is equal to or less than a second threshold value, the second threshold value being less than the first threshold value, is greater than or equal to a second number, the second number being an integer greater than or equal to 1; and exhibit the items categorized into the first number of know type clusters and the second number of unknown type clusters categorized based on the selected clustering standard, wherein the circuitry extracts known items, which are already browsed by the user, from the items based on the browsing history information; the circuitry calculates the probability based on a similarity between an item and the known item using the feature amount information; and the circuitry selects the clustering standard based on the calculated probability.