1. An information processing device comprising: a processor; and a storage, with a predetermined memory space, storing executable instructions that, when executed by the processor, causes the processor to perform as: a cluster information acquisition unit which acquires information indicating a cluster that includes a set of records in an anonymized state, wherein the anonymized state at least a portion of original attribute values of set-valued attributes are removed so that the cluster satisfies a predetermined anonymity, and each set-valued attribute is configured to include at least one value; a refinement attribute selection unit which selects each attribute to be a target of disclosure among attributes that the records include; and a set-valued attribute refinement unit configured to: restore at least a portion of the removed attributes of the selected set-valued attribute to the original attributes of the set-valued attribute, and divide the cluster, using a top-down approach, based on the disclosed attribute value, when the attribute selected by the refinement attribute selection unit is the set-valued attribute.