Kōyōshō and Yakushushō, written by a Buddhist monk of the Shingon school in the late Heian period, Jian Yi, which are used for sacrificial ceremony in Esoteric Buddhism. They are extracted from Chong Guang Bu Zhu Ben Cao, Reading―book for Emperor in XiuWenDian and various buddhist sutras, and copied by Guan You and other monks, truly reflecting stylistic features at that time and having significant research value in literature, language and character. In the process of copying books, sometimes, the content will mutate. These mutations are’t isolated cases, and tend to be systemic. This article discusses the inter-character relationship about 12 groups of regular characters of Kōyōshō and Yakushushō in the Heian period in Japan, and clears out the hidden laws of writing and use of Chinese characters.