Abstract: For efficiently generating training data, a main device includes a processor. The processor performs: a wear determination process of determining, in view of an output signal from a sub-sensor provided close to an odor sensor associated with a service user, whether the odor sensor is worn by the service user; a first acquisition process of acquiring an output signal from the odor sensor; a second acquisition process of acquiring type information indicative of a type of excretion of the service user, which has been determined by a service provider; and a training data generation process of generating h includes sensor information indicative of the output signal having been acquired in the first acquisition process from the odor sensor that has been, in the wear determination process, determined to be worn by the service user and which includes the type information having been acquired in the second acquisition process.