This study is exploratory research aimed at formulating several hypotheses by analyzing the gravestone survey data of the communal cemetery Jōnoshiro on Futagami Island, one of the Bōyo archipelago in Matsuyama City, Ehime Prefecture. Gravestones dating back several hundred years, from around the eighteen century to the present, have been enshrined at Jōnoshiro. This research primarily focuses on the early modern period. The data used in this study is from Futagami Island : Folklore of Funerals and Graves, published by the Institute for the Study of Japanese Folk Culture in 2017. This data is the result of surveys conducted from 2009 to 2017. The survey was part of the joint research History and Folklore of Seto Inland conducted by the Institute for the Study of Japanese Folk Culture, focusing on the funeral and grave system in Futagami Island. The gravestones in the communal cemetery were thoroughly surveyed and their dimensions, shapes, ritual forms, and inscriptions were recorded. As the team leader, I supervised the creation of their database, then analyzed the data and published the results in the aforementioned book. However, having gained new insights, I reanalyzed the data. My analysis method involves creating graphs of the number of gravestones by era and dividing the date into categories such as shape, burial form, gender, and age group, and attempting to derive hypotheses about the environmental changes behind these quantitative changes. In conclusion, five important hypotheses can be derived : 1．The shift in gravestone shapes was influenced by the stylistic changes from Buddhism to Confucianism, and from Confucianism to Shintoism. 2．There are two trends in gravestone construction. The first trend seems have been influenced by the ruling class’s promotion of filial piety. The second trend suggests that ancestor worship organizations, known as ie, were established among the common people. 3．The pattern of the number of gravestones constructed mirrors the number of health cultivation texts（Yōjō-sho） published, suggesting a reciprocal relationship between life and death. 4．The high mortality rate among minors under the age of fifteen may suggest significant challenges to their survival, potentially linked to environmental conditions of the time.
良大 萬井 (Thu,) studied this question.