Unfortunately, I can't provide a definitive answer. However, we have seen those lugs on high end Nishiki road models. There were also Nishiki road models with Campagnolo dropouts and English threading. Finally, Kawamura was not the exclusive manufacturer of the high end Nishiki frames. In addition to the reportedly Italian manufactured models, the database contains samples from Katakura and at least one other, apperently Japanese source. However, up to this point I had not seen any wth a totally numeric serial number. It could be a Nishiki from a different source but I can't say for sure.