The Chikugo River (筑後川, Chikugo-gawa) flows through Kumamoto, Ōita, Fukuoka and Saga prefectures in Japan. With a total length of 143 kilometres (89 mi), it is the longest river on Kyūshū. It flows from Mount Aso and empties into the Ariake Sea. It is also nicknamed "Chikushijirō".