I just received these IJA Sergeant Major shoulder rank tabs, today.
I'm not sure about the date of manufacture, but I heard these were established in Meiji 39 (1906).
陸軍 (Rikugun) - Army
曹長 (Souchou) - Sergeant Major
肩章 (Kenshou, Katashou) - Shoulder Rank Tabs
Any comments welcome.