Misuzu Hibiki, mother to Go and the late Kenichi Hibiki and wife to Daisuke Hibiki, anchors her family as they reconstruct the Mach 5 racing car following Kenichi’s death during a test of its experimental engine. Channeling collective grief into purpose, she collaborates with her husband and surviving son to integrate the "Safety Seven" safety system into the rebuilt vehicle, ensuring Kenichi’s vision of driver protection endures. Misuzu embodies steadfast stability and emotional resilience, guiding Go as he steps into competitive racing to fulfill his brother’s ambitions. Her presence fosters unity amid adversity, balancing quiet strength with a commitment to preserving family bonds and Kenichi’s legacy. The series confines her portrayal to her familial role, omitting personal history or individual narrative beyond these connections.