Graduating top-of-the-class from Suzuka Circuit Racing School Formula (SRS-F) in 2016, Toshiki Oyu was given a scholarship. The following year, he was fourth in the FIA-F4 Japanese Championship. In 2018 and 2019, Oyu participated in the Japanese Formula 3 Championship.
In 2020, Oyu joined the SUPER GT GT300 class to finish fourth, and in his sixth SUPER FORMULA round, clinched his first victory. He finished the season sixth.
Oyu moves up to the SUPER GT GT500 class in 2021, aiming for the top with Ukyo Sasahara. In his second SUPER FORMULA season, Oyu pairs up with 2018 / 2020 champion Naoki Yamamoto, aiming to consistently battle at the top. The result was 16th in the GT500 class and 5th overall in SUPER FORMULA.
In 2022, the same team was in the same position and experienced its first podium finish in the GT500 class.