Miho Nonaka became an Olympic medalist and a dominant force in bouldering after beginning her international senior circuit career in 2013. Nonaka initially focused on competition lead climbing but shifted her attention to bouldering in 2014, securing her first World Cup medal with a second-place finish at the Boulder World Cup in Laval, France, that same year. She finished the 2014 World Cup season ranked fifth overall in bouldering, demonstrating her immediate impact in the discipline. Her consistent performance continued into 2015, where she achieved third place in the overall Boulder World Cup rankings.
She continued her strong performance into 2022, securing a Gold Medal at the World Games in Birmingham for bouldering and finishing second in the overall Boulder World Cup rankings. Maintaining her elite position, Nonaka secured second place in the overall Boulder World Cup rankings in 2023, a year that also saw her claim a Gold Medal at the IFSC World Cup in Seoul for bouldering. In 2024, she once again qualified for the Summer Olympics in Paris, participating in the combined bouldering and lead event and finishing ninth in the semifinals, reinforcing her sustained presence at the highest echelons of competitive climbing.