Japanese boxing superstar Naoya Inoue remained the undisputed world super-bantamweight champion when Irish challenger TJ Doheny dropped to his knee and quit in the seventh round because of an apparent back injury on Tuesday. Doheny complained of a “twinge” after walking back to his corner gingerly. Before then, he was getting pummeled by Inoue, who celebrated his technical knockout — for a 28th successive win — in muted fashion in Tokyo.