Imai Nobume began life as Mukuro, an orphan molded into a professional assassin by the Tenshouin Naraku faction. Guarding the imprisoned Yoshida Shouyou exposed her to emotions and knowledge, foreign concepts to her assassin's existence. Her lethal proficiency earned her status among Naraku's elite "Three Feathers." Four years before the main events, her assassination mission against the Hitotsubashi family was sabotaged by Sasaki Isaburo. Naraku punished Sasaki severely, costing him his wife and infant child. Mukuro arrived moments too late to intervene, killing several Naraku assassins involved. Though initially accused of the murders by Sasaki, he uncovered the truth and spared her. He took her in, renaming her "Nobume" – the name meant for his lost daughter – and tasked her with eventually killing him as his atonement. Nobume possesses a triangular face, dull red eyes, and long dark blue hair framed by evenly trimmed bangs. A Yatagarasu tattoo hides behind her neck. Initially pupil-less, reflecting her emotionless conditioning, her eyes gained pupils after Sasaki's death, marking her emotional awakening. She typically wears modified Mimawarigumi attire featuring blue half-thigh shorts, X-patterned socks, and a long trench coat. Earlier, she wore a kimono or an outfit similar to Katsura's, often with her hair in a ponytail. Trained as a cold-blooded killer, Nobume exhibited emotionless expressions and speech, coupled with sadistic tendencies; she found visceral satisfaction in cutting down opponents. Sasaki described her indiscriminate killing as her "assassin mode." She displayed obsessive behavior, particularly regarding donuts, reacting violently to obtain them or if teased. Loyal to Sasaki, she still disobeyed orders based on her conscience, such as aiding Rotten Maizou. She harbored deep hatred for authority figures like the Tendoushu who abused power. Her emotional depth surfaced when she cried over her mission to kill Sasaki and mourned his death. After his demise, she declared independence, vowing to kill only by her own will, not for factions. She formed protective bonds with allies like Soyo Hime and Kagura, forming the "Sisterhood Sadist Three." Her dynamic with Sakata Gintoki involved unspoken synchronization during missions. A lethal swordmaster raised in assassination, Nobume wields a katana with a concealed tantō in the scabbard, employing a two-sword style. Kondo Isao likened her to a grim reaper due to her precision. Her exceptional endurance allowed her to survive building collapses and severe injuries, continuing fighting despite mortal impalement. Additional skills include expert voice imitation, used to impersonate the Shogun, and acute perceptiveness, enabling her to discern others' true natures, like Okita Sougo's sadism or the sorrow within Gintoki and Takasugi. Following Sasaki's death, Nobume ascended to director of the police department, refusing subservience to external forces. She upheld her ideals of justice, rejecting service to the Tendoushu and declaring her autonomy to Utsuro.