My Companion Insisted I Wash My Hands of the Past

Tsuboi Kikue is a fifteen-year-old assassin operating in Yokohama, a city where supernatural abilities are commonplace. She possesses an ability called "Jet-Black Wings," which manifests as large, non-flying black wings that serve as shields, blades, and propulsion tools. The power is fueled by her embarrassment and requires her to shout dramatic, chuunibyou-style slogans to activate; the more cringey the chant, the stronger the ability becomes. Despite her effectiveness, the embarrassing nature of her power has forced her to work alone, as other assassins find partnering with her socially awkward. She ranks among the top three killers in Yokohama but maintains a low profile to protect her real identity.

Oda Sakunosuke is a fourteen-year-old assassin known simply by his real name, ranking number one in the city. He is characterized by his emotionless demeanor, red hair, and exceptional combat skills, which appear to include precognition. Unlike Kikue, who kills for money and survival, Oda kills with mechanical precision and no emotional attachment. After years of solitary work, Oda decides to quit the profession after reading a novel with a torn-out ending. He wishes to understand human life to write his own stories, so he donates all his earnings and resolves to never kill again. His last contract is to eliminate Kikue, who had carelessly become entangled in a corporate power struggle.

When Oda confronts Kikue, he effortlessly defeats her, recognizing her inferior skill. However, instead of killing her, he offers her a choice: join him in his new life or die. Kikue, facing certain death and the ongoing threat from the conglomerate that hired him, accepts his offer. Oda reveals he will protect her from future threats despite his vow not to kill, establishing a partnership based on mutual survival rather than romance. They begin living together in Kikue’s small apartment, navigating the transition from assassins to civilians.

The two struggle to adapt to ordinary life. Kikue seeks stable employment, taking a job at a convenience store and recruiting Oda as a part-time worker. Oda approaches this new experience with philosophical curiosity, asking Kikue about human emotions and the meaning of life. Kikue, who has always lived for survival and money, finds Oda’s abstract questions difficult but tries to guide him. Their dynamic shifts as Kikue takes on a protective, almost maternal role, managing their finances and daily routines while Oda remains passive and compliant.

As they settle into their new routine, former associates and enemies begin to resurface. The conglomerate that originally hired Oda sends assassins to eliminate Kikue, believing she is still a threat. Kikue fights them off using her Jet-Black Wings, but Oda intervenes, incapacitating the attackers without killing them, thereby honoring his vow while ensuring Kikue’s safety. This incident solidifies their bond, with Kikue realizing that Oda’s presence provides a security she never had as a solo operative.

The pair encounters Edogawa Ranpo, a young detective with a deductive ability, and his bodyguard, the Silver Wolf. Ranpo quickly deduces Kikue’s identity as the Jet-Black Wings based on her behavior and relationship with Oda. This encounter highlights the contrast between the criminal underworld and the emerging detective world in Yokohama. Oda’s interactions with Ranpo and the Silver Wolf reveal that his past actions have left a mark on other key figures in the city.

Kikue and Oda continue to search for a sustainable career path. Kikue considers opening a bakery or dessert shop, inspired by Ranpo’s gluttony, while Oda remains open to any opportunity, though he lacks direction. Their relationship evolves into a deep companionship, characterized by unspoken trust and shared history. Despite the lack of romantic declaration, their daily lives together suggest a profound intimacy forged through shared trauma and the transition from killers to ordinary youths. The story follows their attempts to build a future in a city that refuses to let them easily leave their past behind.