Sirius no Kizuato

When Takeru Tachibana was ten years old, an enemy air raid devastated his hometown, killing his parents and leaving him mortally wounded. Unable to cope with the crushing weight of survivor’s guilt and the prospect of living alone, his older sister Sayoko made a desperate choice. She sold her brain to the Albion Corporation, led by the enigmatic CEO Véltare Marçeau, to fund the risky surgery that saved Takeru’s life. The procedure transferred her consciousness into a cybernetic body, erasing her memories and amplifying her aggression. Reborn as "The White 13"—known in the arena as "The Ice Doll"—she spent five years battling other cyborgs on a brutal gladiatorial dogfight circuit, ultimately rising to become the grand champion under the rank of Sirius. Now fifteen, Takeru has finally rescued his sister from the fighting rings, only to uncover a devastating secret: outside the circuit, a built-in self-destruct mechanism is slowly killing her. He has exactly one week to find a cure or return her to the arena before she dies. Complicating his desperate mission is the relentless pursuit by the Albion Corporation, determined to reclaim their stolen property, alongside a cast of scarred individuals whose own tragic pasts intertwine with his struggle to save the only family he has left.