Since swimming practice was widely encouraged as anuniversal movement throughout the nation and swimming lessons were included in the official curriculum of primary schools, this kuroneko fundoshi loincloth became popular across the country as swimming pants for children covering from infants to students of elementary schools and it could be found here and there in Japan until around 1955.
国民皆泳が叫ばれ水泳が学校の教科として取り上げられたことで、幼児～小学生用の水着として全国に普及し、昭和30年代頃まで各地で散見されていた。