Hi Chase, your stamp seems to be a forgery - which is very often the case for classics Japanese stamps. Indeed it is a well known forgery made by Wada, and I reckon it is Wada Plate 23 or 24, Syllabic 14. It does match the design features described in the following link (see "Unsigned" forgeries, Wada Plate 23 and 24 - no shading west of bottom "6" in "6 Sen").
https://japanstamps.org/2021/08/20/...elow-buckle/The postmark, although very faint, should be the often used fake "Tokyo Mozou " double circle date stamp.
So, even it is a forgery, it's definitely worth keeping !
- Hironobu