Research on eelgrass beds in Japan began with the “Fish Growth Survey in Eelgrass beds” conducted by the Okayama Prefectural Fisheries Experiment Station from 1922 to 1925. Eelgrass beds are known to be the “cradle of the sea” with many roles and functions, such as promoting material cycle, suppressing water temperature rise, supplying dissolved oxygen, absorbing nutrients, and absorbing and accumulating carbon dioxide. Eelgrass beds and oyster farming have a symbiotic relationship. Oyster shells nurture eelgrass beds, which in turn nurture oysters. In the Hinase area of Okayama Prefecture, there were approximately 590 ha of eelgrass beds until the 1950s, but by the 1980s the area had plummeted to about 12 ha. Fishermen in the Hinase area began planting eelgrass seeds in 1985, and through various efforts, the area has recovered to over 250 ha by 2015. Environmental factors related to eelgrass vegetation include water temperature, salinity, ground surface, light flux transmission, waves and currents, bottom sediment, and seafloor migration. Important elemental technologies leading to large-scale eelgrass bed restoration include “Guidelines for Eelgrass Bed Creation Techniques” and “Guidelines for Effective Utilization of Oyster Shells”. Today, not only fishermen, but also children, urban residents, people living in Satoyama, people engaged in agriculture, and various other stakeholders inside and outside the community find value in interrelationships centering on fishermen, and are joining forces to protect the local sea, transcending regions, generations, and positions. Hinase Town’s “Satoumi creation” will serve as a model for what coastal zone management should look like in the future.