1. An information processing device communicating with a memory system, wherein the memory system comprises a nonvolatile memory comprising a first namespace including first erase unit areas and a second namespace including second erase unit areas, and a controller controlling the nonvolatile memory, the information processing device is external to the memory system, the information processing device comprises a processor executing first to fourth programs, and the processor assigns, when a first characteristic feature of a first logical address space corresponding to the first program and a second characteristic feature of a second logical address space corresponding to the second program are different, the first and second logical address spaces to the first namespace, assigns, when a third characteristic feature of a third logical address space corresponding to the third program and a fourth characteristic feature of a fourth logical address space corresponding to the fourth program are different, the third and fourth logical address spaces to the second namespace, transmits a write command, identification data of a namespace assigned to a logical address space corresponding to the write command, write data, and logical address of the write data, to the controller, and transmits a read command, the identification data, and a logical address of read data, to the controller, and receives the read data from the controller.