Gunji faced the WGP Kickboxing veteran, and the promotions former champion, Facu Suarez in the quarterfinals bout of the 2022 K-1 Featherweight World Grand Prix, which was held at K-1 World GP 2022 in Fukuoka on August 11, 2022. Despite a slow start to the fight, which saw one of the judges score the opening round as a draw, Gunji would go on to dominate the remaining two rounds en-route to winning the bout by unanimous decision. Two judges scored the fight 30–27 for him, while the third judge scored the fight 30–28 in his favor. Gunji advanced to the penultimate bout of the one-day tournament, where he faced the reigning Krush Featherweight (-57.5kg) champion Shuhei Kumura, who earned his place in the semifinals with a second-round stoppage of Jawsuayai Sor.Dechaphan. Gunji won the fight by knockout, stopping Kumura with a right straight at the very last second of the first round. Advancing to the finals, Gunji faced Toma Tanabe, who he had beaten by an extra round decision on April 3, 2022. He won the rematch by a first-round technical knockout.
