Since the amount of gold contained in one ryo against Koban (former Japanese oval gold coin) and Ichibuban was held down as well as Nishukin gold coin and Nibukin gold coin, Isshukin was used as subsidiary coin.
二朱金、二分金とともに小判、一分判に対し一両あたりの含有金量が低く抑えられ、補助貨幣的に用いられた。