He most recently competed in Moto3 from 2016 to 2023, where he finished runner-up in his final year in the category behind eventual champion Jaume Masià.

For the 2019 Moto3 World Championship, Sasaki would stay with Petronas Sepang Racing Team, but would be partnered by John McPhee.

Sasaki switched teams for the 2020 Moto3 World Championship, signing with Red Bull KTM Tech3, to partner Deniz Öncü.

On May 29, 2021, in the 2021 Italian motorcycle Grand Prix, Sasaki was involved in an accident with Jason Dupasquier and Jeremy Alcoba.

For 2022, Sasaki is contracted to race for Sterilgarda Husqvarna Max team, along with 2019 teammate John McPhee.