Miyuki Sakaigawa (surname combining "world" and "river," given name meaning "deep happiness/luck") drums for GYROAXIA. A third-year dentistry student at Kamogawa Music College Faculty of Dentistry after moving to Tokyo, he previously practiced kickboxing. He switched to drumming seeking greater popularity. His combat sports background fuels his powerful drumming style, using natural strength to deliver rhythmically intense and flashy performances that create a distinct impression.

As one of GYROAXIA's older members, Miyuki maintains a generally stoic exterior. He consistently shows friendliness towards children and women. However, he exhibits marked hostility towards bandmate Kenta Satozuka, clashing strongly over Kenta's management policies and approaches.

While Miyuki admires vocalist Nayuta Asahi, he explicitly rejects Kenta's philosophy of discarding one's humanity for Nayuta's sake. This ideological conflict forms a significant tension point within the band.