How to use USB virtual COM port

/*

GR-SAKURA USB Virtual Serial Comm Port Example
To use a virtual serial port, you must use the dedicated driver "GRSAKURA.inf" for Port (COM and LPT).
The USB driver "GRSAKURA.inf" selects COM4: がじぇっとルネサス SAKURA (COM4).

Original of this example: http://japan.renesasrulz.com/gr_user_forum_japanese/f/4/t/82.aspx

GR-SAKURA COM Driver Location: http://japan.renesasrulz.com/cfs-filesystemfile.ashx/__key/telligent-evolution-components-attachments/00-04-01-00-00-00-04-13/sakura_2D00_vcom_2D00_drv.zip

*/
#include <rxduino.h>
int count;
void setup() {
    Serial.begin(38400); // opens a virtual serial port. the baud rate parameter does nothing.
    pinMode(PIN_LED3, OUTPUT);
}

void loop() {
    if(Serial.available()) {                 // If any key is hit,
        Serial.write(Serial.read());
        digitalWrite(PIN_LED3, ++count & 1); // LED D4 turns on.
    }

}