[6] His seven fight winning streak earned Koudai a chance to challenge Yoshiho Tane for the DEEP KICK -53kg championship at DEEP☆KICK 34 on December 17, 2017.
[9][10] Koudai faced Ponchan OZgym at Suk Wanchai MuayThai Super Fight vol.5 on September 24, 2019.
Koudai was next booked to face Yuuichi at HOOST CUP KINGS OSAKA 3 on October 28, 2018.
[21][22] Hiroyama faced Kazuki Osaki in a non-title bout at HOOST CUP KINGS OSAKA 4 on October 27, 2019.
[27] Hirayama was expected to face Koki Osaki in a tournament reserve match at RISE WORLD SERIES 2021 Yokohama on September 23, 2021.
[31] Koudai faced Azusa Kaneko at HOOST CUP KINGS KYOTO 9 〜REVERSAL〜 on March 27, 2022.
[33] After successfully snapping his two-fight losing skid, Koudai was scheduled to face Ryu Hanaoka at RISE 159 on June 24, 2022.
[36] Koudai faced Auto Muangphapoon in a -55kg bout at HOOST CUP KINGS KYOTO 10 on October 16, 2022.