He raced in the same series till 2019 where he claimed 3rd in the standings behind Ren Sato, and Atsushi Miyake.

Kawaii moves up to Super GT - GT300 with Saitama Toyopet GreenBrave, paired up with Hiroki Yoshida.

[2] In his debut season, he managed to get a win and podiums which claimed him, and Yoshida to Second in the standings behind to Kondo Racing of Kiyoto Fujinami & João Paulo de Oliveira.

[5] In 2023 Saitama Toyopet GreenBrave retained both Kawaai & Hiroki Yoshida and they claimed 2 wins and 4 podiums.

[1] Kawaai went on to win the 2023 Super GT Championship in the GT300 class alongside Yoshida.