[2] Monguchi was scheduled to make his second professional appearance against Kojiro Flysky Gym at RISE 127 on September 16, 2018.
[4] Monguchi fought another Target Shibuya gym representative, YA-MAN, at RISE 130 on February 3, 2019.
[8] He won the fight by a convincing unanimous decision, with all three judges awarding him every single round of the bout.
[12] Monguchi suffered the first loss of his professional career at the hands of Masaki Takeuchi at RISE 145 on January 30, 2021.
Kaito utilized his longer reach to win the closely contested bout by split decision, with scores of 30–29, 30–29 and 29–30.
[18] He won the fight by a first-round technical knockout, after successfully knocking Ozaki down three times by the 1:51 minute mark of the opening round.
[21] Monguchi faced Kotaro Yamada in a Shootboxing rules bout at RISE WORLD SERIES / SHOOTBOXING-KINGS on December 25, 2022.
[23] Monguchi faced the former Krush Featherweight champion Takahito Niimi at RISE EL DORADO 2023 on March 26, 2023.
[25] Monguchi faced the former two-weight Shootboxing champion Kyo Kawakami in a non-title bout at RISE World Series 2023 - 1st Round on July 2, 2023.