Satoyama is the term for Japan's traditional buffer zone between mountain and farmland, a patchwork of ponds, rice paddies, and waterways that has supported both people and wildlife for generations. The film settles into one such landscape to watch what lives there: fish moving through flooded fields, water birds working the shallows, snakes and dragonflies filling out a food web that depends on centuries-old irrigation habits rather than untouched wilderness. At the center is Sangoro Tanaka, an 83-year-old fisherman who still works the waters by hand, using methods passed down rather than modernized, and whose daily routine becomes the film's argument for what sustainable land use can actually look like in practice. There is little narration pushing a thesis; the camera mostly stays with Tanaka and the creatures sharing his water, letting the relationship between the two carry the point. It is a quiet case study in an ecosystem built by human hands and kept alive by one man still keeping up the work that built it.