Osaka Prefectural Gymnasium
On February 28, 2014, Ioka would vacate the WBA title to move up to the flyweight division in order to attempt becoming a three division world champion. On May 7, 2014, Ioka faced Thai IBF champion Amnat Ruenroeng at the Osaka Prefectural Gymnasium. Ioka seemed to be the more active boxer but Ruenroeng landed heavier blows while countering Ioka. Ruenroeng lost a point for hitting after the break. Nevertheless, Ruenroeng retained his title with a split decision (119-108, 115-112, 113-114). The 119-108 card turned in by judge Pawel Kardyni was criticized as being far too wide.