Chitaru Namatame, also known as Namatame Chitaru, holds prominence in the series. Her family history remains undisclosed, yet she forged a deep bond with her former teacher's daughter. This individual's assassination by the killer Angel Trumpet drove Chitaru to transfer into Class Black at Myojo Academy. Unlike other assassins targeting Haru Ichinose, her singular objective was identifying and eliminating Angel Trumpet to grant her grieving mentor closure, a mission shaping her every action.

Physically, Chitaru stands at 171 cm with short red hair and red eyes, projecting a tall, mature demeanor. Her typical attire includes a black coat featuring yellow outer lining over a white collared shirt, gray pants, and black shoes. This ensemble contributes to her princely aura and older-than-actual-age presence among peers.

Chitaru's personality blends honor, protectiveness, and fierce justice. She exhibits kindness and care, especially toward vulnerable individuals like Hitsugi Kirigaya and Haru Ichinose, explicitly stating early on she would not harm Haru. Her protective instincts manifest in constant support for Hitsugi, guiding her when lost and accompanying her frequently. Despite this principled exterior, Chitaru harbors vengeful determination against Angel Trumpet. This conflict erupts when she discovers Hitsugi's true identity as the killer, forcing her to confront her affection for Hitsugi against her thirst for retribution.

Her expertise lies in swordsmanship, evidenced by calloused palms from relentless training. She wields a blade with formidable skill, rivaling elite fighters like Tokaku Azuma. During Myojo Academy's Venus Festival, Chitaru plays Romeo in a stage production where her hunt for Angel Trumpet culminates. The revelation of Hitsugi's identity diverges across media: the manga shows Chitaru finding a tranquilizer in Hitsugi’s teddy bear, while the anime depicts her initially suspecting Haru before Hitsugi confesses. Faced with choosing justice for her mentor’s daughter or love for Hitsugi, Chitaru stabs Hitsugi mid-play. In the manga, she selects a knife labeled "justice" over "love"; the anime presents a direct stabbing. Upon learning Hitsugi’s wish was to live with her, Chitaru ingests the remaining poison to die alongside her.

Both survive due to an antidote Hitsugi administers and subsequent medical aid. Chitaru endures a prolonged, bedridden recovery from the poison. During convalescence, she wrestles with guilt over her actions and her fractured relationship with Hitsugi, whom she cannot forgive immediately. Ultimately, they choose to live together, forging a complex but enduring bond. Their expulsion from Class Black is symbolized by red roses on Chitaru’s desk, signifying love.