The reason for the appearance of these variants is that there is a difference in the recognition of language culture and Buddhist culture in each country. This study compared and analyzed morphologically the Japanese and Chinese lexicons, focusing on Japanese lexicons. Of the 7,818 words, the most common (2,236, i.e., 28.6%) were Korean, Chinese, and Japanese. The number of Japanese/Chinese isomorphic variants was 1,885 (24.1%), and the number of Japanese/Chinese isomorphous variants was 1,578 (20.2%). In addition, 2,119 words (27.1%) appeared as the only four-letter words in Japanese.
As a result of the comparison, the Korean, Chinese, and Japanese isomorphs were most frequently investigated, which is similar to the research result of Zhang (2018). Japanese and Chinese isomorphs were more common than Japanese and Korean isomorphs. This is similar the result of Hayashi’s (2013) study, but opposite to the result of a study by Zhang (2018). Japanese-only four-letter words have a relatively low ratio compared to Hayashi’s (2013) results.
There were variant patterns in the Korean, Chinese, and Japanese characters. For example, “a part of a four-letter word that differs in part,” “a four-letter word that has a different word order,” and “a case where there is no four-letter word corresponding to each country.” The reason for the appearance of these variants was the difference in the recognition of language culture and Buddhist culture in each country, or the result of the reduction and recombination of Chinese words.