In the Nintendo DS Games, she uses a Sun Dying Will Flame.A reason for this could be due to the fact that every student of Kokuyo Junior High modifies their uniform in one way or another as stated in Vongola 77. Later on, her uniform changed to a new one, but it was still different from Chrome's.
It's possible that the reason M.M wears a different uniform from Chrome's is that it's the school's band uniform, thus complimenting that fact that her weapon is a Clarinet.Burning Vibrato - Using the Clarinet, it sends heat waves of vibrating atoms that explode on contact.Clarinet - M.M can transform her clarinet into nunchucks for close-combat.Despite having a slightly selfish and mean personality, she does have a positive side to her which is shown when she tells Chrome that Mukuro was just using her, expressing her concern. She cares a lot about fashion and money and prefers to date rich men. Her appearance doesn't change much in the future except for a new yellow M-shaped hairclip. M.M wore a green Kokuyo uniform during the Kokuyo Arc, while in the future, she was dressed in a short-sleeved light purple shirt and in her mug shot she's wearing a black blouse and a dark purple jacket, nail polish, and a black choker. In the manga, both her hair and eyes are reddish, but in the anime, she has red hair and violet eyes.