1. An information processing system comprising: a first processor that executes instructions belonging to a first instruction set; a second processor that executes instructions belonging to a second instruction set; a first memory that stores a translation target program that is designed based on the first instruction set, the first memory being unaccessible by the second processor; a second memory that is accessible by the second processor; and a data transfer unit that transfers data between the first memory and the second memory, wherein the first processor operates to: read the translation target program from the first memory; determine whether each instruction included in the translation target program is a memory access instruction for accessing data stored in the first memory; translate the instructions that are determined to be not the memory access instruction into translated instructions belonging to the second instruction set; and translate the instructions that are determined to be the memory access instruction into an instruction sequence including a call instruction calling a data transfer library for controlling the data transfer unit to transfer the data between the first memory and the second memory, the data transfer library being stored in the second memory, and wherein the second processor operates to: execute the translated instructions that belong to the second instruction set; and control the data transfer unit to transfer the data between the first memory and the second memory in accordance with the call instruction included in the instruction sequence.