A printer including: a receive buffer that receives string information indicating a strong including one or more substrings; a storage storing data defined by a specific rule; a command string generator that generates, for each substring in the string information received by the receive buffer, a command string including a command and the substring based on information stored in the storage indicating the style of each sub string, a command executor that generates image data according to the one or more commands in the one or more command strings generated by the command string generator; a print buffer for storing the image data generated by the command executor; and a printing mechanism that prints based on the image data stored in the print buffer.