Ryota Murata, the first Japanese boxer to win both an Olympic and professional world championship, said Wednesday that he has effectively retired.

The 37-year-old middleweight lost his WBA super world title to IBF champion Gennady Golovkin of Kazakhstan via a ninth-round technical knockout in their title unification bout last April.

"Inside my head I'm thinking, 'that was my last,'" Murata said of the defeat. "I just haven't been able to announce it (until now), but that's how I'm thinking personally."

The Nara Prefecture native earned silver at the 2011 world championships before winning an Olympic gold medal in 2012, Japan's second in boxing and the country's first in 48 years.

After making his professional debut in August 2013, Murata won the WBA title in October 2017 against Hassan N'Dam of France in a seventh-round technical knockout.

The title came five months he lost to the Frenchman in a controversial decision that saw two judges suspended after ruling in N'Dam's favor.

Murata lost his second title defense a year later against Rob Brant but reclaimed the belt with a TKO of the American in their July 2019 rematch.

Murata ends his professional career with 16 wins, including 13 by knockout, and three defeats. His bout against Golovkin came after a two-year, four-month absence from the ring due to the pandemic.

He was 119-19 as an amateur.