WBA super-featherweight super champion Takashi Uchiyama (23-0-1, 19 KOs), 129.5, an unbeaten KO artist of Japan, retained his throne as he displayed a finest knockout in his career by stretching previously unbeaten Thailander Jomthong Chuwatana (9-1, 4 KOs), 129, with a pulverizing right at 1:15 of the second round on Wednesday in Tokyo, Japan.