Kazuki Shinatora enters boxing as Kyoto's representative in the Champion Carnival, driven by vengeance against his father. This animosity stems from a childhood kendo training incident where his father subjected him to a high-speed ventilator, permanently damaging his right hand and forcing exclusive reliance on his left. Initially fragile under paternal brutality, he later conquered the ventilator challenge by retrieving three balls at blinding speed, proving his resilience.

During the Champion Carnival semifinals, he deployed his Rolling Thunder technique against Ryuji Takane but lost. He subsequently joined Golden Japan Jr., refining his style with Special Rolling Thunder variants and defensive maneuvers like Miracle Defense and Circle Moon. In the Pacific War against Team USA, he defeated Hell Mick using Rolling Thunder.

Kazuki briefly retired in the Shadow Clan arc yet returned to combat the lethal boxing faction alongside teammates. Competing in Golden Japan Jr.'s flawless-victory campaign at the World Tournament, he battled Greek opponents including Ulysses, momentarily overcoming his right-hand disability in combat.

His evolution shifted from cold indifference toward revenge to embracing team loyalty. Relationships include his sister Futaba Shinatora and son Iori Shinatora, featured in sequels. A rivalry with Takeshi Kawai emerged during the Champion Carnival, though Kazuki initially dismissed it.

His background incorporates rigorous kendo training under his father using the sword Bizen Ozasune, with techniques like Engetsu-ken reflecting swordsmanship principles. Post-boxing retirement, he mentored successors including his son Iori and sequel protagonist Rindō Kenzaki.