The code stamped on your caseback—often read as or GN4WS12G —is not the model number or the movement (calibre) number.
The watch is designed to automatically set the time and date by receiving radio waves at 3:00 AM or 4:00 AM daily. This is the most convenient way to ensure accuracy. To check the reception result, simply press button (B) located at the 4:00 position. The second hand will point to a reception result (H, M, or L for success, or NO for failure). If the automatic reception fails or you are in an area without signal coverage, manual setting is required. citizen eco drive gn4ws12g manual link
Rotate the crown clockwise or counterclockwise to adjust the minutes and hours. The code stamped on your caseback—often read as