Hyō Shimaki holds the title of Black Cat Knight among the Beast Knights, partnered with Coo Ritter. Initially presented as an intellectually driven professor, he pursues the Akashic Records, the repository of all universal knowledge. This ambition attracts the series antagonist, Animus, who seeks to recruit Shimaki by promising shared cosmic exploration. Shimaki seemingly considers the offer before rejecting it and launching an attack against Animus.

His initial contractual wish for omniscience was denied by Coo Ritter. Consequently, he gained the power of ultimate conceptualization, Kybele, enabling him to create and control personalized golems. These constructs grow progressively more powerful throughout the narrative. Early golems are designated using German weekdays; upon exhausting these names, he adopts German seasonal names. His escalating combat effectiveness is demonstrated by defeating Maimakterion—an opponent Samidare Asahina could not overcome—and later toppling the mountain-sized golem Poseidon. Concerns exist regarding his potential to eventually create a golem rivaling Samidare's final battle capabilities.

Initially reserved and enigmatic, Shimaki's early characterization emphasizes a selfish pursuit of knowledge. However, his development reveals genuine concern for his fellow knights. He explicitly dislikes alcohol. His relationship with fellow knight Yayoi Hakudou develops significantly, culminating in their marriage, as revealed in the series epilogue set ten years after the final battle.

Physically, he possesses standard human attributes without his powers. His golems exhibit subsonic speed and destructive capacity scaling from building level to small city level. His domain control ability, Gaia, facilitates earth manipulation and golem creation. He possesses superhuman reaction times and notable stamina for sustained combat.

His surname "Shimaki" combines characters meaning "wind" (風) and "volume/roll" (巻), while his given name "Hyō" translates to "leopard" or "panther" (豹).