In a 2006 study in Japan, it was discovered that out of the whole country, Yamagata Prefecture, along with Aomori Prefecture, had the highest amount of marine plastic waste drift onto its shores. Thanks to the 20-year cooperation among a variety of bodies across different regions, a section of the coast improved enough that it was possible to walk on it barefoot, albeit temporarily. I would like to reflect on the background of those clean-up activities, as well as think about future actions for the adult generation obligated to carry them out.