[3] In 2021 he continued to race in the F4 Japanese Championship with the Honda Formula Dream Project team.

[4] Koide ended up winning the F4 Japanese Championship title ahead of his teammate Yusuke Mitsui.

Koide continues to compete in the series, as he moves to B-Max Racing Team.

[6] He is also set to compete in the GT300-class of the 2023 Super GT Series with Team UpGarage alongside Takashi Kobayashi.

[3][7] Koide won his first GT300 race in the first round of the series in Okayama International Circuit.