Hyakunosuke Ogata, born near Tokyo and raised in Ibaraki Prefecture, was the illegitimate son of Imperial Japanese Army Lieutenant General Koujirou Hanazawa. Abandoned by Hanazawa, Ogata's mother descended into mental illness, fostering his cynical worldview and driving his obsession with paternal validation. He inherited his father's distinctive angular "staple-like" eyebrows and dark, catlike eyes, earning him the nickname "Wildcat" or "Yamaneko". He attained the rank of Superior Private in the 7th Division, fighting in the Russo-Japanese War at the Siege of Port Arthur and Battle of 203 Hill. His service honed exceptional sniping skills using a Type 30 Arisaka rifle, supported by acute hearing, mental fortitude for stakeouts, and concealed fluency in Russian. Ogata embodied coldblooded calculation and emotional detachment, viewing killing as pragmatic and patricide a "rite of passage." He believed all humans possessed his capacity for remorseless violence, experiencing cognitive dissonance when confronted with contrary evidence. A pivotal event was the murder of his younger half-brother, 2nd Lieutenant Yuusaku Hanazawa. Influenced by his grandmother and Lieutenant Tsurumi's suggestion that removing Yuusaku would win their father's affection, Ogata shot him during combat. This act triggered profound, suppressed guilt that destabilized his psyche, compounded by Hanazawa's unwavering rejection regardless of Yuusaku's fate. After the war, Ogata pursued the hidden Ainu gold independently. His initial encounter with Saichi Sugimoto and Asirpa near Otaru turned violent: Sugimoto broke Ogata's arm and jaw before Ogata fell down a cliff into a freezing river. He survived near-fatal hypothermia, rescued by 7th Division soldiers who found him mysteriously aided on the riverbank—implied to be Kiroranke. Upon recovery, Ogata betrayed the 7th Division, abandoning his military buzzcut for an undercut symbolizing liberation. He allied with Kiroranke's group, later shifting allegiance to Hijikata Toshizo's faction. Throughout the gold hunt, he oscillated between tentative alliances and betrayals. He manipulated Asirpa for her connection to the tattooed skins, yet displayed unexpected behaviors like sniffing her hand akin to a cat investigating scents. He also saved Sugimoto from a fake Ainu attacker, indicating complex transactional dynamics. Ogata sustained significant injuries, including symmetrical facial scars from the cliff fall and the loss of his right eye to Asirpa's poisoned arrow—later replaced with a prosthetic. He survived a dynamite explosion in the Yubari mines, persisting despite severe wounds that underscored his resilience despite close-combat vulnerabilities. Ogata's psychological decline intensified. Suppressed guilt over Yuusaku's death manifested as suicidal ideation; he explicitly desired Asirpa to kill him. This culminated during the train confrontation in Karafuto. Poisoned by aconite from Asirpa's arrow—amplifying his anxiety—and facing Sugimoto after failing to assassinate Tsurumi, Ogata provoked Asirpa into shooting him. His death served as a catalyst for Asirpa and Sugimoto's resolve against Tsurumi, fulfilling his role as a tragic figure consumed by self-destructive choices stemming from childhood trauma and misguided justifications.