Martha Hatter

Martha Hatter is Sophie Hatter's youngest sister. It is said that the youngest of three is the one who will make their fortune in life, so Martha was considered blessed by birth.

Howl's Moving Castle (Book)
Martha Hatter is Sophie's youngest sister. She is slender and fair with big grey eyes, but known to be the smartest of the three Hatter sisters. As such, Fanny arranges her to become Mrs. Fairfax's apprentice, though Martha and Lettie Hatter switch appearances temporarily in order to switch places. Martha happily works as an apprentice Cesari's, a renowned pastry shop, and her ambition is to get married and have ten children. She loves Michael Fisher.

Trivia

 * Though never shown or talked about in the movie, Martha does have a tiny cameo. When Sophie makes her way to the foothills of the nearby mountains and passes a farmer's cottage, the farmer makes a mention of her saying she "was looking for her younger sister."  This sister would be Martha, who would still be with Mrs. Fairfax up in the hills, if Lettie was still in Market Chipping.