Taking his first two wins in the Asia Talent Cup upon its inauguration in 2014, Ayumu Sasaki then took the crown the following year, as well as racing in the Red Bull Rookies Cup and gaining his first victory there. Racing in the FIM CEV Repsol Moto3™ Junior World Championship in Valencia in 2015, the Japanese rider took a podium first time out. His meteoric rise continued in 2016, as he was Red Bull Rookies Champion and sixth in Moto3™ in the CEV. With one appearance in the World Championship with Gresini Racing Moto3™ to replace injured title-contender Enea Bastianini, Sasaki raced full time on the world stage in 2017 with the SIC Racing Team and took the title of Rookie of the Year. The team was re-named Petronas Sprinta Racing for 2018, and Sasaki remained for his sophomore season. He took two front row starts and some top 10 finishes despite some struggles with fitness. 2019 saw Sasaki take a debut pole position, but a debut podium still eluded him despite fighting inside the top five at some points throughout the year. For 2020, the Japanese rider switched teams and manufacturers, riding for Red Bull KTM Tech 3. After a frustrating start to the year, including two great rides at the Red Bull Ring that ended without reward, 'Crazy Boy' finally tasted podium success at the Aragon GP with a second place finish. Sasaki opened up 2021 with several top six finishes, but injuries sustained from a heavy crash at the Catalan GP saw interrupted his progress. Following his injury return, the number 71 claimed P3 in Aragon, helping him to a ninth place Championship finish. A move to Sterilgarda Max Racing Team came in 2022, and the Japanese rider had an excellent year, with two victories and seven further podiums seeing him claim P4 in the Championship. Remaining on Husqvarna machinery, the #71 was considered a favourite for the title in 2023 and lived up to expectations. Consistently on the podium throughout the year, the Japanese rider ultimately finished second despite a victory in Valencia and made the switch to Moto2™ in 2024 under the Correos Prepago Yamaha VR46 Team banner. It was a learning year for the Japanese rider, with a best result of 12th at the Aragon GP, with a total of seven points scored across the season. Now in 2025, he moves to the RW Racing GP squad with an exciting in-store for the Japanese rider.