Ryukyu Islands - Okinawa - Museum Gallery

Sho Tai, 1848-1879. Hanshu Ryuukyuu Tsuuhou - obverse is written Ryuukyuu Tsuuhou in seal script; reverse reads "Han Shu" in seal script (half a Shu). Obverse characters: Ryu Kyu Tsu Ho (Ryukyu Currency)
These are relatively scarce. The edge has a ("sa") character stamped, a bit off center, that can best be described as a cross w/double cross hatch (contact me for photo). I have a Ryukyu 100 Mon which is gorgeous example. To see this and another example go to Ancient>Oriental Cast>Japan>Ryukyu Islands - here's a link:
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The round Hanshuu Ryuukyuu Tsuuhou was ordered to circulate at the value of 248 mon, or twice the value of the 100 mon coin. However it weighed merely 8 monme or about 10 to 12 times the weight of the average one mon coin. Han means "half" and "shu" is a gold currency weight. Therefore the Satsuma government was trying to command an exchange rate between copper currency and gold currency. Normally the relative exchange rates of silver, gold and copper currencies were unstable throughout Japan despite government attempts to decree them into one currency system. Thus although at one half shu this coin should have circulated at 32 coins per gold ryou (one koban coin), it is unlikely that it really did so. See David Hartill's ""Early Japanese Coins" for details and different story/history.
Source: Nihon Ginkou Chousakyoku ed., Zuroku Nihon no kahei, vol. 4 (Tokyo: Touyou Keizai Shinpousha, 1973), pp. 319-322. From Luke Robert's "East Asian Cash" website.
Made by Satsuma Domain, which also controlled Okinawa at that time. The value of the coin was intended tobe 1/32 Ryō. However, at the time the exchange rate was around 6700 Mon for 1 Ryō, resulting the value above 200 Mon. It is said that the coin was intended for the double vale of the Tōhyaku coin.
Half a shu was the equivelant of 125 mon, however the value quickly declined to half of that (62.5 mon). [Numista.com]

A variety of this type is described as: (S Album auction #21 Lot 1550, Jan 2015)
RYUKYUS: Iyemochi, 1858-1866, AE � shu, ND (1863), Cr-115, H-6.29var, with character shu stamped on the edge, tall thick characters.
I can confirm that the characters appear slightly larger and are thicker, thus the Hartill H-29 var designator.