Mars Noir, also known as Black March, is one of the thirteen legendary weapons known as the 13 Month Series, created by the blacksmith Ashul Edwaru for King Zahard. It takes the form of a B‑rank needle and is a sentient weapon, containing the spirit of a young woman. This spirit is described as having a strong, fiery temperament and an independent will; she does not easily accept any wielder and only grants her power to those she deems worthy. Her motivations are tied to the ancient purpose of the 13 Month Series—closely linked to King Zahard’s plans and the mystery of the Tower’s 135th floor—yet as a living blade, she also seeks a bond with a compatible user. In the story, Mars Noir first appears when Princess Yuri Zahard lends it to Bam (Twenty‑fifth Bam) during his initial test on the first floor, allowing him to survive and progress. This act defies tradition and sets in motion a chain of events. Throughout the early arcs, Mars Noir accompanies Bam, and the spirit inside develops a connection with him, reflecting his growth and the deepening intrigue surrounding the 13 Month Series. Later, the weapon is returned to Yuri, but its influence persists. Notable abilities include its keen cutting power, the spirit’s supernatural strength, and its capacity to channel shinsu energy when the wielder is accepted. Its personality is volatile and discerning, making it both a unpredictable tool and a symbol of the secrets that govern the Tower.