Storage device, electronic system including storage device, and control program for storage device

In one embodiment, a storage device that is installable in an electronic apparatus includes a first communication interface for connecting the electronic apparatus to the storage device, a nonvolatile memory for storing data and data management table storing a data size and address information for the data stored in the nonvolatile memory, and a processor configured to change at least one piece of data stored in the nonvolatile memory without changing file management information stored in the data management table. The processor is configured to change the stored data without receiving an instruction to do so from the electronic apparatus through the first interface.