OVA
Description
Reki emerges as a pivotal supporting character, originating from the secluded Ulus tribe of Mongolia where she resided among 46 other women. This tribe contends with a genetic condition resulting solely in female births, compelling their quest for robust external males to fortify their lineage. She claims direct descent from the historical figures Minamoto no Yoshitsune and Genghis Khan. After an unexplained release from seclusion, she enrolled at Tokyo Butei High School, rising to become the S-ranked ace of the Snipe department.

Physically, Reki stands 152 cm tall with pale skin and striking bright yellow eyes. Her aquamarine hair, altered by prolonged exposure to Ririirokane, frames her petite figure. She invariably wears Sennheiser PMX990 headphones during missions, stating they "keep her soul intact." Her attire is initially limited to school uniforms, only expanding to casual wear after receiving gifts. Kinji observes her figure as "not as flat as Aria, but not as well endowed as Shirayuki," noting slight breast growth in later volumes.

Initially nicknamed "Robot Reki" for her emotionless exterior, she speaks sparingly and maintains stoic indifference, even in vulnerable moments. This stems not from an absence of feeling, but an inability to comprehend or convey emotions. Her personality features steadfast obsessiveness, particularly in maintaining her Dragunov sniper rifle to near-impossible reliability standards. She claims to follow orders from an entity called the "Wind," perceived as delusional by Kinji. Yet, she reveals a soft spot for animals, demonstrated when she swiftly tames a wolf named Haimaki and adopts it as her Butei partner.

Her combat prowess centers on sniping, achieving a 100% accuracy rate within a 2,051-meter range. She utilizes specialized techniques like "L-snipe" and "Eight Ship Leap." Her equipment includes a Dragunov sniper rifle with a bayonet, later augmented by a Barrett M82 under special authorization. Additional skills encompass knowledge of animal physiology—enabling non-lethal spinal paralysis shots—and extreme environmental endurance honed in Mongolia. Her signature pre-shot mantra reinforces her detached focus: "I am a single bullet. It has no heart. Therefore, it does not think. It just flies straight towards its target."

Relationships significantly shape her development. She forms fierce loyalty to Kinji Tohyama after he becomes the first to evoke genuine human emotions within her. This culminates in a culturally motivated forced marriage proposal in Volume 6, delivered at gunpoint. Her bond with fellow S-rank Aria Kanzaki is marked by mutual respect, though they clash as romantic rivals. Within Team Baskerville, she provides sniper support alongside Kinji, Aria, Shirayuki, and Riko. Later, she exhibits jealousy towards Kinji's interactions with Moe Mochizuki and others.

Character evolution unfolds across the light novels. In Volume 7, coerced by Juujuu CaoCao, Reki nearly commits suicide, halted only by a one-in-a-trillion misfire from Kinji's sabotaged rifle intervention. This pivotal event shifts her worldview, leading her to adopt Kinji's philosophy: "In the midst of this darkness. A path of light exists..." Subsequent volumes depict her gradual expression of anger, jealousy, embarrassment, and her first smile. She transfers schools to follow Kinji in Volume 12, receiving the temporary surname "Yada" from him. Her unwavering loyalty culminates in declarations like "I am yours. The loyalty of the Ulus is eternal. I will be with you wherever you go."