Daito Seiki Co., Ltd.(Nishi Ward, Tokyo), 1953-60
DSK made exact copies of the BMW R-25 (DSK A-25), R-51 (DSK A-50) and R-26 (DSK AB-25). Another source also mentions a series of 2 stroke machines, but I haven't been able to confirm that. According to their Wikipedia page (in Japanese) BMW allowed them to sell domestically in Japan so long as they didn't export them, although that seems a bit odd. The factory burned down in 1957 and although an attempt was made to resume production they were gone by 1960.
Other cloners of BMW machines included: BIM, Rikuo and the Tsubasa G120.