[5] Jin was scheduled to fight Tatsuya Tsubakihara during Hoost Cup Kings Kyoto 2.
[12][13] He fought Koki Osaki during RISE 135, and won the bout by unanimous decision.
[20] During the Kyushu Professional Kickboxing vol.2 event, Mandokoro fought Tatsuya Hibata for the WBKF World Super Flyweight title.
[26] Mandokoro was scheduled to face Yu Hiramatsu at Rizin Trigger 1 on November 28, 2021.
[27] Mandokoro was booked to face Syuto Sato at Rizin 34 – Osaka on March 20, 2022.
[30] He lost the fight by a third-round technical knockout, due to doctor stoppage.
He won the fight by a second-round technical knockout, after thrice knocking Seoane down.
Mandokoro was able to avenge his loss to Hanaoka, as he won the fight by a first-round knockout, and advanced to the finals, where he faced Kaito Hasegawa.
Mandokoro captured the tournament title, as well as the right to challenge RISE Super Flyweight champion Kazuki Osaki, by unanimous decision.