In 1897 Baldwin delivered 24 Atlantic-type locomotives to the Nippon Tetsudo, remaining the only Japanese locomotives of this wheel arrangement. In design terms, they followed a typical American Atlantic pattern, but were scaled down for the 3 ft 6 in Cape gauge and the considerably more restrictive loading gauge. Thanks to the trailing axle and the space-saving bar frame, the firebox could be placed entirely behind the driving axles and made unusually wide, an arrangement that was otherwise difficult to achieve on narrow-gauge steam locomotives. Characteristic American features included the large cab and the high-mounted running boards. The inside Stephenson valve gear of American design gave the locomotives a relatively uncluttered appearance, as only the connecting and coupling rods were visible externally.

On the initially private railway, they were classified as Bbt2/5 and carried operating numbers 506 to 529, serving on what is today the Jōban Line on Japan’s east coast. Although the available coal was of poor quality, the large grate area allowed the boiler to maintain a high steam output. Following nationalisation in 1906, the locomotives were renumbered 6600 to 6623 by Japanese National Railways (JNR). As only two of the five axles of an Atlantic locomotive were powered, they were soon superseded by newer superheated steam locomotives with higher adhesive weight. All 24 locomotives were withdrawn and scrapped in April and May 1925.