[3] A rematch followed, and Harada lost the title in his first defense, being outpointed by Kingpetch over fifteen rounds on January 12, 1963 in Bangkok, Thailand.

Among the boxers he beat was top contenders Ray Asis, Oscar Reyes, and Katsutoshi Aoki.

[5] On November 30, he defeated perennial British contender Alan Rudkin by a fifteen round decision to retain the title.

Losing for the second time to Harada prompted Jofre to retire; he would make a successful comeback three years later.

On January 3, 1967, Harada retained his world bantamweight title with a fifteen round decision over Medel in Nagoya.

On February 27, 1968, Lionel Rose became the first Indigenous Australian to become a world boxing champion, when he outpointed Harada over fifteen rounds in Tokyo.

His lone loss during that span came at the hands of American Alton Colter by a ten round, split decision.

The fight was held in Sydney, and the referee and only judge was the legendary former world featherweight champion Willie Pep.

On January 28, 2004, as he was driving home from his office, Harada experienced a headache and he was found to have a brain hemorrhage which required hospitalisation.

[9] On November 7, 2019 he presented the Muhammad Ali Trophy to Naoya Inoue after his victory over Nonito Donaire to win the 2018–19 World Boxing Super Series – bantamweight division tournament.