In the late 16th century, leaders of the Shiwaku Navy were named as the official headmen of different districts, and the positions were inherited by their descendants. The first headmen were from the Irie, Miyamoto, Yoshida and Maki families, and the graves of some of those families still stand on Honjima. The earliest is from 1626, during the time when Osaka Castle was built, and in later years graves more than three meters high were erected for successive generations.