Money changer’s manuscript coin detector and double sided gold coin counting board. The coin detector has many hand drawn illustrations of coins with their weights, characteristics etc.The gold coin counting board (Kanemasu) is very unusual as it is double sided and appears to have slightly different sizes for the ‘Ichibuban’ rectangular gold coin. These are the small rectangular gold coins as drawn in the volume. This counting board was used to speed up transactions by a money changer. The Ichibuban gold coin was the equivalent of 1/4 ‘ryo.’ The ryo was the basic unit of monetary counting, in particular gold. A single ryo was worth about 60 ‘monme’ of silver, or about 4,000 copper coins. There were 4 Ichibuban coins in one ‘Koban’ coin, which was 1 ryo. 10 Koban coins, or 10 ryo, made up 1 ‘Oban’ which was the largest gold coin.

Thus there were 40 Ichibuban coins in one Oban coin. Both sides of the counting board have 80 slots to hold 80 Ichibuban coins. Thus, filling all 80 slots would be equal to 20 ryo, or 20 Koban, or 2 Oban. The difference is the sizes of the slots are probably due to debasement of the gold coins during this era. The counting board also shows the hand punched crest seal of the money changer.