Ayato Kirishima, younger brother to Touka Kirishima, grew up in Tokyo's 20th Ward with their father Arata. Arata stressed blending into human society through libraries and human food, but Ayato rejected this, convinced ghouls could never be normal among humans. After their mother Hikari's death, Arata vanished during a scavenging trip, captured by CCG investigators. Betrayed by family friend Satou who fed them human food and alerted investigators, forcing Touka to use her kagune to escape, Ayato solidified his hatred for humans and distrust of cooperation. Yoshimura took in the siblings at Anteiku, yet Ayato grew increasingly violent. When Touka befriended her human classmate Yoriko, Ayato condemned such interaction as dangerous folly and abandoned Anteiku. Wandering Tokyo's wards, he seized feeding grounds by force, causing chaos that attracted Aogiri Tree executive Tatara. Ayato joined Aogiri, rising to executive status due to his combat prowess. He adopted the alias "Black Rabbit" to divert CCG attention from Touka's own "Rabbit" moniker. Ayato initially displayed an arrogant, brash personality, driven by the conviction that "the world is power" and the weak deserve to perish, a perspective rooted in his parents' deaths. He lashed out verbally and physically at perceived weakness, kicking subordinates for failures and dismissing compassion. He harbored deep resentment toward Arata, viewing him as weak for prioritizing coexistence, and projected this hatred onto Ken Kaneki due to Kaneki's similar demeanor. Despite his cruelty, Ayato unconsciously protected Touka; during Aogiri's capture of Kaneki, he incapacitated her to prevent Yamori from torturing her, an act Kaneki later interpreted as hidden concern. Loyal to Aogiri, Ayato oversaw operations like Kaneki's abduction and defended their hideout during CCG raids. He battled Touka there, criticizing her weakness and consuming part of her kagune, but was defeated by Kaneki, who broke 103 of his bones while revealing Ayato's suppressed desire to protect his sister. Post-recovery, Ayato participated in key missions, including the raid on Dr. Kanou's lab and the Cochlea prison break. During Cochlea, he confronted investigator Yukinori Shinohara, recognizing his father's kagune used in Shinohara's Arata armor, triggering fury over Arata's fate. Over three years, Ayato's personality matured significantly. He retained tactical ruthlessness but shed much arrogance, adopting a calmer, more rational demeanor. As Aogiri's security lead during the Auction arc, he prioritized subordinate safety: defying Tatara's orders to aid Naki against Juuzou Suzuya's squad and refusing to abandon Hinami Fueguchi, expressing visible distress at her capture. After Aogiri abandoned Hinami, Ayato allied with Banjou to plan her rescue, later joining Kaneki's ghoul organization, Goat, under the One-Eyed King. He participated in the Cochlea raid to free Hinami, reconciling with Touka, who stated he no longer needed to protect her. Key relationships persisted through his development. His bond with Touka evolved from hostility to uneasy alliance, though he hid softer impulses, like denying interest in visiting her daughter. He treated Hinami as a respected partner, shielding her from tasks like killing and fiercely advocating for her rescue. His dynamic with Kaneki shifted from disdain to acceptance, recognizing him as a leader and brother-in-law. Ayato also demonstrated loyalty to allies like his maternal uncle, Renji Yomo, who aided him during the Cochlea raid. A natural ukaku ghoul, Ayato generated wing-like kagune from his shoulders, firing crystalline projectiles or hardening them for close combat—an unusual adaptation mitigating the ukaku's typical close-range weakness. His abilities included high-speed regeneration, surviving multisystem trauma like Kaneki's assault, and acute auditory perception. Post-timeskip, his kagune expanded in size and control, enabling techniques like the "One-Wing" formation. The CCG rated him SS-level.