Miyuki Sakaigawa is the drummer of the band GYROAXIA and a university student pursuing a degree in dentistry. He is one of the older members of the group, standing out with a calm and collected demeanor that contrasts with his somewhat flashy appearance. Despite a surface impression that might suggest a casual or playful attitude, he is actually quite stoic and serious underneath. He is known for being friendly and considerate toward women and children, and he often serves as a mediator within the band, especially when tensions arise between vocalist Nayuta Asahi and guitarist Reon Misono. His motivation for joining the band originally came from a desire for popularity; he previously trained as a kickboxer before switching to drums, using his natural physical strength to deliver a powerful, attention-grabbing rhythm. He values hard work and considers his musical talent to be limited, making up for it with relentless effort. Within the story of Gekijō-ban Argonavis Axia, which centers on GYROAXIA facing internal conflict and rumors of disbandment, Miyuki plays a stabilizing role. He admires Nayuta as a vocalist but strongly disagrees with the management approach of Kenta Satozuka, the band’s leader, particularly Kenta’s belief in sacrificing personal humanity for the sake of Nayuta’s artistic vision. This difference creates notable tension between them. Miyuki’s development in the movie involves reconciling his loyalty to the band with his own principles, navigating the pressures that threaten to tear GYROAXIA apart. His key relationships are defined by this friction with Kenta, his respect for Nayuta, and his protective, harmonizing presence among the other members.