These twelve Mikados were built by Baldwin in 1918 for express freight service. They were classified by Baldwin as type 12-38 ¼ E, what stands for twelve wheels, eight of these powered, trucks in the front and rear, and a cylinder diameter of 22 inches. Designed for rails of 80 pounds per yard, they had an axle load of less than 40,000 pounds, making them some of the smaller standard-gauge Mikados built by Baldwin. For service in express freight service, their drivers measured 57 inches, what was a bit larger than the 54 inches of the other Mikados of the Mantetsu. They shared many similarities with the Pacifics 901 to 912 which were built two years later by the same manufacturer.