Ritsuhin Motorcycle Research Institute, 1936-1953
Not a lot of information available. They made 500cc and 350cc 4 stroke models and in 1953 they also offered a 250cc ohv version under the Riturin name which is shown below The location of the business was listed as being in Fukushima-ku, Osaka. An alternate manufacturer name in some documentation is Creative Laboratory (Fukushima-ku, Osaka City). No doubt more details will become available.