120 locations 24 Region Prefecture Rivers, harbors and lakes in which microplastics were present Hokkaido Hokkaido Abira River, Yufutsu River, Pacific Ocean Kanto Tokyo Arakawa River, Kottagawa River, Okuri River, the canal near Shibaura Park, the canal near Shibaura Island Tower, Tennozu Canal, Keihin Canal, Tokyo Bay, Tamagawa River, Nogawa River, Kanda River, Nihonbashi River, Sendaibori River, Sumida River, Meguro River Saitama Arakawa River, Tonegawa River, Fukukawa River, Karasawa River, Nakagawa River Chiba Tateyama Bay, Choshi Port, Tonegawa River, Lake Teganuma Ibaraki Tonegawa River, Lake Kasumigaura Chubu Aichi Toyokawa River, Umeda River Yamanashi Shiokawa River, Fuji River, Arakawa River, Byodo River, Fuefuki River Shizuoka Matsuge River, Sakai River, Oba River, Goten River Kansai Osaka Ishizu River, Higashiyoke River, Hazama River, Yamato River Shiga Sofu River, Chagama River, Lake Biwa, Setagawa River Hyogo Osaka Bay (Port of Kobe) Kyoto Chiji River, Toshitani River, Nango Pond, Nishikawa River, Hozugawa River Mie Ago Bay, Matoya Bay, Kaizou River Chugoku Okayama Sunagawa River, Sasagase River, Kurashiki River, Ashimori River Kyushu Fukuoka Umi River Kagoshima Amori River, Korida River