In 1876, a new numbering system was introduced under which odd numbers were used for locomotives used in Eastern Japan (between Tokyo and Yokohama) and even numbers were used for locomotives used in Western Japan (between Osaka and Kobe).
1876年（明治9年）には、東部（京浜間）の機関車を奇数に、西部（阪神間）の機関車を偶数とする改番が実施された。