Speed King calls it a day
Former WBC super-bantamweight champion Toshiaki Nishioka has retired, a month after losing to Nonito Donaire of the Philippines.
"I have done what I should do. I am fully satisfied with my boxing career," the 36-year-old Japanese southpaw said on Tuesday.
"I have experienced excitement many times through 18 years as a pro boxer."
Nishioka, nicknamed "Speed King" for his fast-paced fighting style and feared for his devastating straight left, made his professional debut in 1994 and became WBC super-bantamweight champion in 2008.
Making his seventh defence, he beat Mexican Rafael Marquez in Las Vegas last December. He was named WBC "emeritus champion" on March 15, leaving the regular title vacant.
It was taken over by Mexico's Abner Mares on April 21 when he beat Puerto Rican Eric Morel in El Paso, Texas.
IBF and WBO champion Donaire stopped Nishioka in the ninth round of their super-bantamweight title unification fight in Carson, California, on October 13. Nishioka was knocked down twice in his first defeat in eight years.
"I am confident of becoming champion again if I fight boxers other than Donaire," said Nishioka, who is set to open a gym and train young boxers.
"But I cannot think of any better fight than the one I had with him."
He is retiring with a professional record of 39 wins, including 24 knockouts, five losses and three draws.
Donaire said in a statement he felt proud to have fought a "speedy and brainy boxer" such as Nishioka and sent his best wishes to the Japanese fighter.