Ioka, 24, is currently in his second reign at two weight divisions, making a successful first defence by knocking the Thai fighter out in the ninth round and improving his record to 12-0 in the process.
Earlier, another undefeated champion in Ryo Miyazaki also defended his WBA minimumweight belt for the first time by stopping Mexican Carlos Velarde in five rounds to the delight of the home crowd.
24 year-old Miyazaki improved his record to 19-0-3 with his eleventh knockout win and may now look for a unification in the coming months before moving up the weights.
