Old Vintage Seikosha 15 Jewel Pocket Watch Railroad Engraved Back

This vintage Seikosha 15 jewel pocket watch is working and has Japanese characters engraved on the back. We believe it is a Japanese railroad watch and the number on the back signifies the specific train it was used on but do not know for sure. It was brought back by a US military officer who was stationed in the Pacific during the 1960s. There is a crack in the dial but other than that it is in nice condition.