A communication system including at least a first information processing terminal and a second information processing terminal that are communicable with each other, the first information processing terminal comprising: obtaining means for obtaining, from outside, a multiplay program which allows users of at least the first information processing terminal and the second information processing terminal to play the same game together and a basic software update program for updating basic software in the second information processing terminal such that the multiplay program is executable on the second information processing terminal; program storage means (35a, 44a) for storing the multiplay program and the basic software update program that have been obtained by the obtaining means; first transmission means (311, S74, S87) for transmitting the multiplay program or the basic software update program which is stored in the program storage means, to the second information processing terminal in accordance with a request from the second information processing terminal; and first multiplay process means for executing the multiplay with the second information processing terminal, and the second information processing terminal comprising: first reception means (311, S49) for receiving the basic software update program from the first information processing terminal; first basic software update means (311, S50) for updating basic software of the second information processing terminal by using the basic software update program received by the first reception means; second reception means (311, S35) for receiving the multiplay program from the first information processing terminal; and second multiplay process means (311, S37) for executing the multiplay with the first information processing terminal based on the multiplay program received by the second reception means. obtaining means for obtaining, from outside, a multiplay program which allows users of at least the first information processing terminal and the second information processing terminal to play the same game together and a basic software update program for updating basic software in the second information processing terminal such that the multiplay program is executable on the second information processing terminal; program storage means (35a, 44a) for storing the multiplay program and the basic software update program that have been obtained by the obtaining means; first transmission means (311, S74, S87) for transmitting the multiplay program or the basic software update program which is stored in the program storage means, to the second information processing terminal in accordance with a request from the second information processing terminal; and first multiplay process means for executing the multiplay with the second information processing terminal, and first reception means (311, S49) for receiving the basic software update program from the first information processing terminal; first basic software update means (311, S50) for updating basic software of the second information processing terminal by using the basic software update program received by the first reception means; second reception means (311, S35) for receiving the multiplay program from the first information processing terminal; and second multiplay process means (311, S37) for executing the multiplay with the first information processing terminal based on the multiplay program received by the second reception means.