The Shoku Nihongi (Chronciles of Japan, continued) mentioned that Wado-kaichin, made of silver, were issued in May 708, the minting of the copper Wado-kaichin coins began in July of the same year, and the copper coins were issued in August of that same year.
708年5月には銀貨が発行され、7月には銅貨の鋳造が始まり、8月に発行されたことが続日本紀に記されている。