4. The system according to claim 3 , wherein the static converter further comprises: a second replacement section for replacing a character string output instruction whose character code set has been previously converted into the second code set, with a second buffering instruction for adding, to the second buffer, a character string whose character code set has previously been converted into the second code set.
5. The system according to claim 4 , wherein the dynamic converter further comprises: a first replacement section for replacing each of a plurality of character string output instructions which have not been converted into the second buffering instructions, with a first buffering instruction for adding a character string, which is to be outputted, to the first buffer, without converting the character code set from the first code set; and an instruction insertion section for inserting a conversion instruction into a part of the output program executed before the second buffering instruction and after the plurality of first buffering instructions, the conversion instruction collectively converting a character code set of a plurality of character strings stored in the first buffer into the second code set, and then adding the converted character strings to the second buffer.