Subaru Hoshikawa, the Rooster Knight, is a red-haired warrior trained alongside Yukimachi Tsukishiro, the Tortoise Knight, under Akitani Inatika—a 500-year-old clairvoyant linked to the universe’s omniscient deity. Recognizing their destiny, Akitani mentored the pair as his final act before sacrificing himself to save them from a golem’s assault.

Subaru and Yukimachi inherited Akitani’s immense power and teachings, ascending to become two of the strongest Beast Knights. By synchronizing their Holding Fields, they forge an "unbreakable shield" and "unstoppable spear," a duality that amplifies their combat synergy. This bond embodies Akitani’s legacy, as he believed their growth pivotal to countering the threat of Animus.

Akitani’s posthumously uncovered journal alluded to his foresight of future conflicts, though it withheld specifics about other Beast Knights beyond Yuuhi Amamiya. Despite their mentor’s death, Subaru and Yukimachi persist in their mission, leveraging their combined strength as both weapon and safeguard against potential betrayals within their order. Their unity remains a strategic linchpin in the ongoing war, reflecting Akitani’s final preparations for a fractured battlefront.