On September 23, 2021, Nahashima was scheduled to face Shohei Asahara, Yasuomi Soda and Yusaku Nakamura in his retirement exhibition match at DEEP☆KICK 55. As in the previous occasion, he came to the match wearing a significant cosplay, the same Miku Hatsune costume he wore in his K-1 championship in November 2008, and thanked the fans for their support in his 14 years career.
