There are three varieties, two struck 1772-1824 (Ko nanryo gin) and one struck 1824-1830 (Shin nanryo gin). The former weight about 10.2 grams, the latter 7.5.
Yes listed as the latter and apparently one of my scans was upside down according to a Canadian coin community member so corrected.....however, just seen Heritage Auctions posted scans as I originally had them.