You are welcome!
Now about the stars in the postmark, it is true that in the regular prewar Japanese domestic postmarks, usually they are no stars in the bottom part. It's usually the time when the postmark has been canceled, for example "am 8-12". However there are postmasks with stars which has been used elsewhere than Hong Kong. In most of the cases, it is an occupied territory but it is not necessarily Hong Kong. I found 1 example of star postmark among my collection. It's a regular Japanese postal stationery with a postmark of Shisuka, now Poronaysk, Russia, during the Japanese occupation of Sakhalin (called Karafuto in Japanese).