1. A non-transitory computer-readable recording medium storing a program for causing a computer to execute a procedure for managing a system that retrieves an image corresponding to a first type specified by a retrieval request received from a terminal device and another image corresponding to a second type associated with the first type, from an image database storing a plurality of images associated with at least a number of a plurality of types, the procedure comprising: referring to learning state information representing whether feature values of each of the plurality of types have been generated, a feature value being used for storing a new image associated with any one of the plurality of types and indicating features of each of the plurality of types, the plurality of types identifying an object captured in the plurality of images; retrieving an unlearned type in which a feature value has not been generated from among the plurality of types, the unlearned type identifying a first object; specifying an association type associated with the unlearned type, the association type identifying a second object associated with the first object; calculating, when the association type has been learned, a distance between the unlearned type and the association type based on a configuration table, the configuration table defining relationships among the plurality of types in a layer format; specifying whether the unlearned type is to be learned based on the calculated distance; outputting recommendation information to learn the feature value of the unlearned type, when the specifying specifies that the unlearned type is to be learned; and outputting the image to the terminal device, wherein the specifying of whether the unlearned type is to be learned is performed prior to the outputting of the image to the terminal device.