[DRG]

http://www.weaponsofwwii.com/forum/viewtopic.php?t=3130

During the mid-1920th Renault tested several new types of suspensions for the FT17/18 tank. IJA was very interested in these developoments and even supported Renault by buying 10 vehicles (5 armed with MG, 5 armed with a gun) tanks from the pre-series production of the NC1 Modellé 1927 and allowing Renault engineers to lead the trials at Kurume in late 1929/early 1930. The results were rather unsatisfying as the suspension made several problems during duration tests.

Nevertheless IJA used a provisional tank unit during the early 1932 Manchurian Incident when chinese warlord troops entered the japanese controlled area around Harbin/Manchuria from northern China but retreated after recognising the tanks. During these operations several NC1tanks, which were now armed with "Sogekiho" 37 mm infantry guns, broke down due to suspension failures. Renault immediately modified several suspension parts after tests with this new configuration in France 1931 were successful. In Europe these vehicles are known as "Renault NC1Modellé 1931" or "NC31". IJA designated both versions "Otsu Gata" = "second (tank) model". During the 1932 Shanghai Incident IJA used some of the modified vehicles. But the suspension still had many problems reducing the operational time. So IJA finally decided to retire the NC1 tanks in late 1932.

another source suggests they were kept around until mid 1940 ..the end date has been adjusted.