Kanon Mitachi

Kanon is the red-haired girl who has killed Nami's brother. She is a carefree, yet an insane and immature girl who kills mostly for her own amusement. Her childish nature is accentuated by her tendency to refer to herself in the third person. Her power is an "Sound Wave" which can make metal explode, with control of her hand. The power is unable to destroy any material expect that with the natural frequency of metal. (Source: Wikipedia)