Houkiboshi is the chef at Kuroneko-tei, a restaurant staffed by automata. She stands 158 cm tall with pale skin, sky blue shoulder-length hair, and garnet red eyes. Her attire includes a deep navy kimono decorated with astrological patterns, a white apron, dark blue high-heeled shoes, a navy blue choker featuring a star, and a hair flower.

Her personality is graceful, polite, and consistently cheerful. She exhibits a nurturing, sisterly presence that brings tranquility to others. Cautious and careful in her conduct, she maintains concern for the other automata's personal backgrounds and strives to remain close to them. She writes daily diary entries without fail and enjoys letter writing. Her culinary expertise is established through her role overseeing kitchen operations.

Manufactured during the early stages of the Great War, she is one of the older automata models. Like the others at Kuroneko-tei, she was originally designed for combat before transitioning to civilian life after the war. A key event in her past involved a period of muteness that ended only when an overwhelming emotional outburst—screaming upon reading her former captain's letter from his sister—restored her voice. She dreams of singing with a powerful voice.

Her name, "Houkiboshi" (箒星), combines "houki" (箒), meaning "broom," and "hoshi/boshi" (星), meaning "star." Her recovery from muteness resulted directly from the emotional catharsis triggered by the letter's contents.